* [PATCH 00/12] Swap-over-NBD without deadlocking v1
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Swapping over NBD is something that is technically possible but not
often advised. While there are number of guides on the internet
on how to configure it and nbd-client supports a -swap switch to
"prevent deadlocks", the fact of the matter is a machine using NBD
for swap can be locked up within minutes if swap is used intensively.
The problem is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need.
Some years ago, Peter Ziljstra developed a series of patches that
supported swap over an NFS that some distributions are carrying in
their kernels. This patch series borrows very heavily from Peter's work
to support swapping over NBD (the relatively straight-forward case)
and uses throttling instead of dynamically resized memory reserves
so the series is not too unwieldy for review.
Patch 1 serialises access to min_free_kbytes. It's not strictly needed
by this series but as the series cares about watermarks in
general, it's a harmless fix. It could be merged independently.
Patch 2 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeying memory.
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 6-9 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean
pages. If packets are received and stored in pages that were
allocated under low-memory situations and are unrelated to
the VM, the packets are dropped.
Patch 10 is a micro-optimisation to avoid a function call in the
common case.
Patch 11 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 12 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get
throttled on a waitqueue if 50% of the PFMEMALLOC reserves are
depleted. It is expected that kswapd and the direct reclaimers
already running will clean enough pages for the low watermark
to be reached and the throttled processes are woken up.
Some basic performance testing was run using kernel builds, netperf
on loopback for UDP and TCP, hackbench (pipes and sockets), iozone
and sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant
performance variances. Here is the results from netperf using
slab as an example
NETPERF UDP
netperf-udp udp-swapnbd
vanilla-slab v1r17-slab
64 178.06 ( 0.00%)* 189.46 ( 6.02%)
1.02% 1.00%
128 355.06 ( 0.00%) 370.75 ( 4.23%)
256 662.47 ( 0.00%) 721.62 ( 8.20%)
1024 2229.39 ( 0.00%) 2567.04 (13.15%)
2048 3974.20 ( 0.00%) 4114.70 ( 3.41%)
3312 5619.89 ( 0.00%) 5800.09 ( 3.11%)
4096 6460.45 ( 0.00%) 6702.45 ( 3.61%)
8192 9580.24 ( 0.00%) 9927.97 ( 3.50%)
16384 13259.14 ( 0.00%) 13493.88 ( 1.74%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 2960.17 2540.14
Total Elapsed Time (seconds) 3554.10 3050.10
NETPERF TCP
netperf-tcp tcp-swapnbd
vanilla-slab v1r17-slab
64 1230.29 ( 0.00%) 1273.17 ( 3.37%)
128 2309.97 ( 0.00%) 2375.22 ( 2.75%)
256 3659.32 ( 0.00%) 3704.87 ( 1.23%)
1024 7267.80 ( 0.00%) 7251.02 (-0.23%)
2048 8358.26 ( 0.00%) 8204.74 (-1.87%)
3312 8631.07 ( 0.00%) 8637.62 ( 0.08%)
4096 8770.95 ( 0.00%) 8704.08 (-0.77%)
8192 9749.33 ( 0.00%) 9769.06 ( 0.20%)
16384 11151.71 ( 0.00%) 11135.32 (-0.15%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 1245.04 1619.89
Total Elapsed Time (seconds) 1250.66 1622.18
Here is the equivalent test for SLUB
NETPERF UDP
netperf-udp udp-swapnbd
vanilla-slub v1r17-slub
64 180.83 ( 0.00%) 183.68 ( 1.55%)
128 357.29 ( 0.00%) 367.11 ( 2.67%)
256 679.64 ( 0.00%)* 724.03 ( 6.13%)
1.15% 1.00%
1024 2343.40 ( 0.00%)* 2610.63 (10.24%)
1.68% 1.00%
2048 3971.53 ( 0.00%) 4102.21 ( 3.19%)*
1.00% 1.40%
3312 5677.04 ( 0.00%) 5748.69 ( 1.25%)
4096 6436.75 ( 0.00%) 6549.41 ( 1.72%)
8192 9698.56 ( 0.00%) 9808.84 ( 1.12%)
16384 13337.06 ( 0.00%) 13404.38 ( 0.50%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 2880.15 2180.13
Total Elapsed Time (seconds) 3458.10 2618.09
NETPERF TCP
netperf-tcp tcp-swapnbd
vanilla-slub v1r17-slub
64 1256.79 ( 0.00%) 1287.32 ( 2.37%)
128 2308.71 ( 0.00%) 2371.09 ( 2.63%)
256 3672.03 ( 0.00%) 3771.05 ( 2.63%)
1024 7245.08 ( 0.00%) 7261.60 ( 0.23%)
2048 8315.17 ( 0.00%) 8244.14 (-0.86%)
3312 8611.43 ( 0.00%) 8616.90 ( 0.06%)
4096 8711.64 ( 0.00%) 8695.97 (-0.18%)
8192 9795.71 ( 0.00%) 9774.11 (-0.22%)
16384 11145.48 ( 0.00%) 11225.70 ( 0.71%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 1345.05 1425.06
Total Elapsed Time (seconds) 1350.61 1430.66
Time to completion varied a lot but this can happen with netperf as
it tries to find results within a sufficiently high confidence. I
wouldn't read too much into the performance gains of netperf-udp
as it can sometimes be affected by code just shuffling around for
whatever reason.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 16*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure. Without the patches, the machine locks up within
minutes and runs to completion with them applied.
Comments?
^ permalink raw reply [flat|nested] 38+ messages in thread
* [PATCH 00/12] Swap-over-NBD without deadlocking v1
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Swapping over NBD is something that is technically possible but not
often advised. While there are number of guides on the internet
on how to configure it and nbd-client supports a -swap switch to
"prevent deadlocks", the fact of the matter is a machine using NBD
for swap can be locked up within minutes if swap is used intensively.
The problem is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need.
Some years ago, Peter Ziljstra developed a series of patches that
supported swap over an NFS that some distributions are carrying in
their kernels. This patch series borrows very heavily from Peter's work
to support swapping over NBD (the relatively straight-forward case)
and uses throttling instead of dynamically resized memory reserves
so the series is not too unwieldy for review.
Patch 1 serialises access to min_free_kbytes. It's not strictly needed
by this series but as the series cares about watermarks in
general, it's a harmless fix. It could be merged independently.
Patch 2 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeying memory.
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 6-9 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean
pages. If packets are received and stored in pages that were
allocated under low-memory situations and are unrelated to
the VM, the packets are dropped.
Patch 10 is a micro-optimisation to avoid a function call in the
common case.
Patch 11 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 12 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get
throttled on a waitqueue if 50% of the PFMEMALLOC reserves are
depleted. It is expected that kswapd and the direct reclaimers
already running will clean enough pages for the low watermark
to be reached and the throttled processes are woken up.
Some basic performance testing was run using kernel builds, netperf
on loopback for UDP and TCP, hackbench (pipes and sockets), iozone
and sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant
performance variances. Here is the results from netperf using
slab as an example
NETPERF UDP
netperf-udp udp-swapnbd
vanilla-slab v1r17-slab
64 178.06 ( 0.00%)* 189.46 ( 6.02%)
1.02% 1.00%
128 355.06 ( 0.00%) 370.75 ( 4.23%)
256 662.47 ( 0.00%) 721.62 ( 8.20%)
1024 2229.39 ( 0.00%) 2567.04 (13.15%)
2048 3974.20 ( 0.00%) 4114.70 ( 3.41%)
3312 5619.89 ( 0.00%) 5800.09 ( 3.11%)
4096 6460.45 ( 0.00%) 6702.45 ( 3.61%)
8192 9580.24 ( 0.00%) 9927.97 ( 3.50%)
16384 13259.14 ( 0.00%) 13493.88 ( 1.74%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 2960.17 2540.14
Total Elapsed Time (seconds) 3554.10 3050.10
NETPERF TCP
netperf-tcp tcp-swapnbd
vanilla-slab v1r17-slab
64 1230.29 ( 0.00%) 1273.17 ( 3.37%)
128 2309.97 ( 0.00%) 2375.22 ( 2.75%)
256 3659.32 ( 0.00%) 3704.87 ( 1.23%)
1024 7267.80 ( 0.00%) 7251.02 (-0.23%)
2048 8358.26 ( 0.00%) 8204.74 (-1.87%)
3312 8631.07 ( 0.00%) 8637.62 ( 0.08%)
4096 8770.95 ( 0.00%) 8704.08 (-0.77%)
8192 9749.33 ( 0.00%) 9769.06 ( 0.20%)
16384 11151.71 ( 0.00%) 11135.32 (-0.15%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 1245.04 1619.89
Total Elapsed Time (seconds) 1250.66 1622.18
Here is the equivalent test for SLUB
NETPERF UDP
netperf-udp udp-swapnbd
vanilla-slub v1r17-slub
64 180.83 ( 0.00%) 183.68 ( 1.55%)
128 357.29 ( 0.00%) 367.11 ( 2.67%)
256 679.64 ( 0.00%)* 724.03 ( 6.13%)
1.15% 1.00%
1024 2343.40 ( 0.00%)* 2610.63 (10.24%)
1.68% 1.00%
2048 3971.53 ( 0.00%) 4102.21 ( 3.19%)*
1.00% 1.40%
3312 5677.04 ( 0.00%) 5748.69 ( 1.25%)
4096 6436.75 ( 0.00%) 6549.41 ( 1.72%)
8192 9698.56 ( 0.00%) 9808.84 ( 1.12%)
16384 13337.06 ( 0.00%) 13404.38 ( 0.50%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 2880.15 2180.13
Total Elapsed Time (seconds) 3458.10 2618.09
NETPERF TCP
netperf-tcp tcp-swapnbd
vanilla-slub v1r17-slub
64 1256.79 ( 0.00%) 1287.32 ( 2.37%)
128 2308.71 ( 0.00%) 2371.09 ( 2.63%)
256 3672.03 ( 0.00%) 3771.05 ( 2.63%)
1024 7245.08 ( 0.00%) 7261.60 ( 0.23%)
2048 8315.17 ( 0.00%) 8244.14 (-0.86%)
3312 8611.43 ( 0.00%) 8616.90 ( 0.06%)
4096 8711.64 ( 0.00%) 8695.97 (-0.18%)
8192 9795.71 ( 0.00%) 9774.11 (-0.22%)
16384 11145.48 ( 0.00%) 11225.70 ( 0.71%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds) 1345.05 1425.06
Total Elapsed Time (seconds) 1350.61 1430.66
Time to completion varied a lot but this can happen with netperf as
it tries to find results within a sufficiently high confidence. I
wouldn't read too much into the performance gains of netperf-udp
as it can sometimes be affected by code just shuffling around for
whatever reason.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 16*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure. Without the patches, the machine locks up within
minutes and runs to completion with them applied.
Comments?
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 38+ messages in thread
* [PATCH 01/12] mm: Serialize access to min_free_kbytes
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
There is a race between the min_free_kbytes sysctl, memory hotplug
and transparent hugepage support enablement. Memory hotplug uses a
zonelists_mutex to avoid a race when building zonelists. Reuse it to
serialise watermark updates.
[a.p.zijlstra@chello.nl: Older patch fixed the race with spinlock]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/page_alloc.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cdef1d4..93afea3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4928,14 +4928,7 @@ static void setup_per_zone_lowmem_reserve(void)
calculate_totalreserve_pages();
}
-/**
- * setup_per_zone_wmarks - called when min_free_kbytes changes
- * or when memory is hot-{added|removed}
- *
- * Ensures that the watermark[min,low,high] values for each zone are set
- * correctly with respect to min_free_kbytes.
- */
-void setup_per_zone_wmarks(void)
+static void __setup_per_zone_wmarks(void)
{
unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
unsigned long lowmem_pages = 0;
@@ -4990,6 +4983,20 @@ void setup_per_zone_wmarks(void)
calculate_totalreserve_pages();
}
+/**
+ * setup_per_zone_wmarks - called when min_free_kbytes changes
+ * or when memory is hot-{added|removed}
+ *
+ * Ensures that the watermark[min,low,high] values for each zone are set
+ * correctly with respect to min_free_kbytes.
+ */
+void setup_per_zone_wmarks(void)
+{
+ mutex_lock(&zonelists_mutex);
+ __setup_per_zone_wmarks();
+ mutex_unlock(&zonelists_mutex);
+}
+
/*
* The inactive anon list should be small enough that the VM never has to
* do too much work, but large enough that each inactive page has a chance
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 01/12] mm: Serialize access to min_free_kbytes
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
There is a race between the min_free_kbytes sysctl, memory hotplug
and transparent hugepage support enablement. Memory hotplug uses a
zonelists_mutex to avoid a race when building zonelists. Reuse it to
serialise watermark updates.
[a.p.zijlstra@chello.nl: Older patch fixed the race with spinlock]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/page_alloc.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cdef1d4..93afea3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4928,14 +4928,7 @@ static void setup_per_zone_lowmem_reserve(void)
calculate_totalreserve_pages();
}
-/**
- * setup_per_zone_wmarks - called when min_free_kbytes changes
- * or when memory is hot-{added|removed}
- *
- * Ensures that the watermark[min,low,high] values for each zone are set
- * correctly with respect to min_free_kbytes.
- */
-void setup_per_zone_wmarks(void)
+static void __setup_per_zone_wmarks(void)
{
unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
unsigned long lowmem_pages = 0;
@@ -4990,6 +4983,20 @@ void setup_per_zone_wmarks(void)
calculate_totalreserve_pages();
}
+/**
+ * setup_per_zone_wmarks - called when min_free_kbytes changes
+ * or when memory is hot-{added|removed}
+ *
+ * Ensures that the watermark[min,low,high] values for each zone are set
+ * correctly with respect to min_free_kbytes.
+ */
+void setup_per_zone_wmarks(void)
+{
+ mutex_lock(&zonelists_mutex);
+ __setup_per_zone_wmarks();
+ mutex_unlock(&zonelists_mutex);
+}
+
/*
* The inactive anon list should be small enough that the VM never has to
* do too much work, but large enough that each inactive page has a chance
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 02/12] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Allocations of pages below the min watermark run a risk of the machine
hanging due to lack of memory. To prevent this, only callers who
have PF_MEMALLOC or TIF_MEMDIE set and not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated
to a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
Pages allocated from the reserve are returned with page->pfmemalloc
set and it's up to the caller to determine how the page should be
protected. SLAB restricts access to any page with page->pfmemalloc set
to callers which are known to able to access the PFMEMALLOC reserve. If
one is not available, an attempt is made to allocate a new page rather
than use a reserve. SLUB is a bit more relaxed in that it only records
if the current per-CPU page was allocated from PFMEMALLOC reserve and
uses another partial slab if the caller does not have the necessary
GFP or process flags. This was found to be sufficient in tests to
avoid hangs due to SLUB generally maintaining smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators
can fail a slab allocation even though free objects are available
because they are being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/mm_types.h | 8 ++
include/linux/slub_def.h | 1 +
mm/internal.h | 3 +
mm/page_alloc.c | 27 +++++-
mm/slab.c | 216 +++++++++++++++++++++++++++++++++++++++-------
mm/slub.c | 35 ++++++--
6 files changed, 246 insertions(+), 44 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 26bc4e2..1a5e14b 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -71,6 +71,14 @@ struct page {
union {
pgoff_t index; /* Our offset within mapping. */
void *freelist; /* SLUB: freelist req. slab lock */
+ bool pfmemalloc; /* If set by the page allocator,
+ * ALLOC_PFMEMALLOC was set and the
+ * low watermark was not met implying
+ * that the system is under some
+ * pressure. The caller should try
+ * ensure this page is only used to
+ * free other pages.
+ */
};
struct list_head lru; /* Pageout list, eg. active_list
* protected by zone->lru_lock !
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 8b6e8ae..f6cdbce 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -38,6 +38,7 @@ struct kmem_cache_cpu {
void **freelist; /* Pointer to first free per cpu object */
struct page *page; /* The slab from which we are allocating */
int node; /* The node of the page (or -1 for debug) */
+ bool pfmemalloc; /* Slab page had pfmemalloc set */
#ifdef CONFIG_SLUB_STATS
unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
diff --git a/mm/internal.h b/mm/internal.h
index 6948820..110c9a2 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -189,6 +189,9 @@ static inline struct page *mem_map_next(struct page *iter,
#define __paginginit __init
#endif
+/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
+
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 93afea3..fb34549 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -647,6 +647,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
trace_mm_page_free_direct(page, order);
kmemcheck_free_shadow(page, order);
+ page->pfmemalloc = false;
if (PageAnon(page))
page->mapping = NULL;
for (i = 0; i < (1 << order); i++)
@@ -1165,6 +1166,7 @@ void free_hot_cold_page(struct page *page, int cold)
migratetype = get_pageblock_migratetype(page);
set_page_private(page, migratetype);
+ page->pfmemalloc = false;
local_irq_save(flags);
if (unlikely(wasMlocked))
free_page_mlock(page);
@@ -1358,6 +1360,7 @@ failed:
#define ALLOC_HARDER 0x10 /* try to alloc harder */
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
+#define ALLOC_PFMEMALLOC 0x80 /* Caller has PF_MEMALLOC set */
#ifdef CONFIG_FAIL_PAGE_ALLOC
@@ -1979,16 +1982,22 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
} else if (unlikely(rt_task(current)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;
- if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
- if (!in_interrupt() &&
- ((current->flags & PF_MEMALLOC) ||
- unlikely(test_thread_flag(TIF_MEMDIE))))
+ if ((current->flags & PF_MEMALLOC) ||
+ unlikely(test_thread_flag(TIF_MEMDIE))) {
+ alloc_flags |= ALLOC_PFMEMALLOC;
+
+ if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
alloc_flags |= ALLOC_NO_WATERMARKS;
}
return alloc_flags;
}
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
+{
+ return gfp_to_alloc_flags(gfp_mask) & ALLOC_PFMEMALLOC;
+}
+
static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
@@ -2167,8 +2176,16 @@ nopage:
got_pg:
if (kmemcheck_enabled)
kmemcheck_pagealloc_alloc(page, order, gfp_mask);
- return page;
+ /*
+ * page->pfmemalloc is set when the caller had PFMEMALLOC set or is
+ * been OOM killed. The expectation is that the caller is taking
+ * steps that will free more memory. The caller should avoid the
+ * page being used for !PFMEMALLOC purposes.
+ */
+ page->pfmemalloc = (alloc_flags & ALLOC_PFMEMALLOC);
+
+ return page;
}
/*
diff --git a/mm/slab.c b/mm/slab.c
index 37961d1f..953e6263 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -120,6 +120,8 @@
#include <asm/tlbflush.h>
#include <asm/page.h>
+#include "internal.h"
+
/*
* DEBUG - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
* 0 for faster, smaller code (especially in the critical paths).
@@ -204,6 +206,7 @@ struct slab {
unsigned int inuse; /* num of objs active in slab */
kmem_bufctl_t free;
unsigned short nodeid;
+ bool pfmemalloc; /* Slab page had pfmemalloc set */
};
/*
@@ -244,15 +247,37 @@ struct array_cache {
unsigned int avail;
unsigned int limit;
unsigned int batchcount;
- unsigned int touched;
+ bool touched;
+ bool pfmemalloc;
spinlock_t lock;
void *entry[]; /*
* Must have this definition in here for the proper
* alignment of array_cache. Also simplifies accessing
* the entries.
+ *
+ * Entries should not be directly dereferenced as
+ * entries belonging to slabs marked pfmemalloc will
+ * have the lower bits set SLAB_OBJ_PFMEMALLOC
*/
};
+#define SLAB_OBJ_PFMEMALLOC 1
+static inline bool is_obj_pfmemalloc(void *objp)
+{
+ return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC;
+}
+
+static inline void set_obj_pfmemalloc(void **objp)
+{
+ *objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC);
+ return;
+}
+
+static inline void clear_obj_pfmemalloc(void **objp)
+{
+ *objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
+}
+
/*
* bootstrap: The caches do not work without cpuarrays anymore, but the
* cpuarrays are allocated from the generic caches...
@@ -885,12 +910,100 @@ static struct array_cache *alloc_arraycache(int node, int entries,
nc->avail = 0;
nc->limit = entries;
nc->batchcount = batchcount;
- nc->touched = 0;
+ nc->touched = false;
spin_lock_init(&nc->lock);
}
return nc;
}
+/* Clears ac->pfmemalloc if no slabs have pfmalloc set */
+static void check_ac_pfmemalloc(struct kmem_cache *cachep,
+ struct array_cache *ac)
+{
+ struct kmem_list3 *l3 = cachep->nodelists[numa_mem_id()];
+ struct slab *slabp;
+
+ if (!ac->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_full, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_partial, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_free, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ ac->pfmemalloc = false;
+}
+
+static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ gfp_t flags, bool force_refill)
+{
+ int i;
+ void *objp = ac->entry[--ac->avail];
+
+ /* Ensure the caller is allowed to use objects from PFMEMALLOC slab */
+ if (unlikely(is_obj_pfmemalloc(objp))) {
+ struct kmem_list3 *l3;
+
+ if (gfp_pfmemalloc_allowed(flags)) {
+ clear_obj_pfmemalloc(&objp);
+ return objp;
+ }
+
+ /* The caller cannot use PFMEMALLOC objects, find another one */
+ for (i = 1; i < ac->avail; i++) {
+ /* If a !PFMEMALLOC object is found, swap them */
+ if (!is_obj_pfmemalloc(ac->entry[i])) {
+ objp = ac->entry[i];
+ ac->entry[i] = ac->entry[ac->avail];
+ ac->entry[ac->avail] = objp;
+ return objp;
+ }
+ }
+
+ /*
+ * If there are full empty slabs and we were not forced to
+ * allocate a slab, mark this one !pfmemalloc
+ */
+ l3 = cachep->nodelists[numa_mem_id()];
+ if (!list_empty(&l3->slabs_free) && force_refill) {
+ struct slab *slabp = virt_to_slab(objp);
+ slabp->pfmemalloc = false;
+ clear_obj_pfmemalloc(&objp);
+ check_ac_pfmemalloc(cachep, ac);
+ return objp;
+ }
+
+ /* No !PFMEMALLOC objects available */
+ ac->avail++;
+ objp = NULL;
+ }
+
+ return objp;
+}
+
+static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ void *objp)
+{
+ struct slab *slabp;
+
+ /* If there are pfmemalloc slabs, check if the object is part of one */
+ if (unlikely(ac->pfmemalloc)) {
+ slabp = virt_to_slab(objp);
+
+ if (slabp->pfmemalloc)
+ set_obj_pfmemalloc(&objp);
+ }
+
+ ac->entry[ac->avail++] = objp;
+}
+
/*
* Transfer objects in one arraycache to another.
* Locking must be handled by the caller.
@@ -1067,7 +1180,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
STATS_INC_ACOVERFLOW(cachep);
__drain_alien_cache(cachep, alien, nodeid);
}
- alien->entry[alien->avail++] = objp;
+ ac_put_obj(cachep, alien, objp);
spin_unlock(&alien->lock);
} else {
spin_lock(&(cachep->nodelists[nodeid])->list_lock);
@@ -1674,7 +1787,8 @@ __initcall(cpucache_init);
* did not request dmaable memory, we might get it, but that
* would be relatively rare and ignorable.
*/
-static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
+static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid,
+ bool *pfmemalloc)
{
struct page *page;
int nr_pages;
@@ -1695,6 +1809,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
page = alloc_pages_exact_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder);
if (!page)
return NULL;
+ *pfmemalloc = page->pfmemalloc;
nr_pages = (1 << cachep->gfporder);
if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
@@ -2127,7 +2242,7 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
cpu_cache_get(cachep)->avail = 0;
cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
cpu_cache_get(cachep)->batchcount = 1;
- cpu_cache_get(cachep)->touched = 0;
+ cpu_cache_get(cachep)->touched = false;
cachep->batchcount = 1;
cachep->limit = BOOT_CPUCACHE_ENTRIES;
return 0;
@@ -2676,6 +2791,7 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
slabp->s_mem = objp + colour_off;
slabp->nodeid = nodeid;
slabp->free = 0;
+ slabp->pfmemalloc = false;
return slabp;
}
@@ -2807,7 +2923,7 @@ static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
* kmem_cache_alloc() when there are no active objs left in a cache.
*/
static int cache_grow(struct kmem_cache *cachep,
- gfp_t flags, int nodeid, void *objp)
+ gfp_t flags, int nodeid, void *objp, bool pfmemalloc)
{
struct slab *slabp;
size_t offset;
@@ -2851,7 +2967,7 @@ static int cache_grow(struct kmem_cache *cachep,
* 'nodeid'.
*/
if (!objp)
- objp = kmem_getpages(cachep, local_flags, nodeid);
+ objp = kmem_getpages(cachep, local_flags, nodeid, &pfmemalloc);
if (!objp)
goto failed;
@@ -2861,6 +2977,13 @@ static int cache_grow(struct kmem_cache *cachep,
if (!slabp)
goto opps1;
+ /* Record if ALLOC_PFMEMALLOC was set when allocating the slab */
+ if (pfmemalloc) {
+ struct array_cache *ac = cpu_cache_get(cachep);
+ slabp->pfmemalloc = true;
+ ac->pfmemalloc = 1;
+ }
+
slab_map_pages(cachep, slabp, objp);
cache_init_objs(cachep, slabp);
@@ -3002,16 +3125,19 @@ bad:
#define check_slabp(x,y) do { } while(0)
#endif
-static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
+static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags,
+ bool force_refill)
{
int batchcount;
struct kmem_list3 *l3;
struct array_cache *ac;
int node;
-retry:
check_irq_off();
node = numa_mem_id();
+ if (unlikely(force_refill))
+ goto force_grow;
+retry:
ac = cpu_cache_get(cachep);
batchcount = ac->batchcount;
if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
@@ -3029,7 +3155,7 @@ retry:
/* See if we can refill from the shared array */
if (l3->shared && transfer_objects(ac, l3->shared, batchcount)) {
- l3->shared->touched = 1;
+ l3->shared->touched = true;
goto alloc_done;
}
@@ -3061,8 +3187,8 @@ retry:
STATS_INC_ACTIVE(cachep);
STATS_SET_HIGH(cachep);
- ac->entry[ac->avail++] = slab_get_obj(cachep, slabp,
- node);
+ ac_put_obj(cachep, ac, slab_get_obj(cachep, slabp,
+ node));
}
check_slabp(cachep, slabp);
@@ -3081,18 +3207,25 @@ alloc_done:
if (unlikely(!ac->avail)) {
int x;
- x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL);
+force_grow:
+ x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL, false);
/* cache_grow can reenable interrupts, then ac could change. */
ac = cpu_cache_get(cachep);
- if (!x && ac->avail == 0) /* no objects in sight? abort */
+
+ /* no objects in sight? abort */
+ if (!x && (ac->avail == 0 || force_refill))
return NULL;
- if (!ac->avail) /* objects refilled by interrupt? */
+ /* objects refilled by interrupt? */
+ if (!ac->avail) {
+ node = numa_node_id();
goto retry;
+ }
}
- ac->touched = 1;
- return ac->entry[--ac->avail];
+ ac->touched = true;
+
+ return ac_get_obj(cachep, ac, flags, force_refill);
}
static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
@@ -3175,23 +3308,35 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
void *objp;
struct array_cache *ac;
+ bool force_refill = false;
check_irq_off();
ac = cpu_cache_get(cachep);
if (likely(ac->avail)) {
- STATS_INC_ALLOCHIT(cachep);
- ac->touched = 1;
- objp = ac->entry[--ac->avail];
- } else {
- STATS_INC_ALLOCMISS(cachep);
- objp = cache_alloc_refill(cachep, flags);
+ ac->touched = true;
+ objp = ac_get_obj(cachep, ac, flags, false);
+
/*
- * the 'ac' may be updated by cache_alloc_refill(),
- * and kmemleak_erase() requires its correct value.
+ * Allow for the possibility all avail objects are not allowed
+ * by the current flags
*/
- ac = cpu_cache_get(cachep);
+ if (objp) {
+ STATS_INC_ALLOCHIT(cachep);
+ goto out;
+ }
+ force_refill = true;
}
+
+ STATS_INC_ALLOCMISS(cachep);
+ objp = cache_alloc_refill(cachep, flags, force_refill);
+ /*
+ * the 'ac' may be updated by cache_alloc_refill(),
+ * and kmemleak_erase() requires its correct value.
+ */
+ ac = cpu_cache_get(cachep);
+
+out:
/*
* To avoid a false negative, if an object that is in one of the
* per-CPU caches is leaked, we need to make sure kmemleak doesn't
@@ -3244,6 +3389,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
enum zone_type high_zoneidx = gfp_zone(flags);
void *obj = NULL;
int nid;
+ bool pfmemalloc;
if (flags & __GFP_THISNODE)
return NULL;
@@ -3280,7 +3426,8 @@ retry:
if (local_flags & __GFP_WAIT)
local_irq_enable();
kmem_flagcheck(cache, flags);
- obj = kmem_getpages(cache, local_flags, numa_mem_id());
+ obj = kmem_getpages(cache, local_flags, numa_mem_id(),
+ &pfmemalloc);
if (local_flags & __GFP_WAIT)
local_irq_disable();
if (obj) {
@@ -3288,7 +3435,7 @@ retry:
* Insert into the appropriate per node queues
*/
nid = page_to_nid(virt_to_page(obj));
- if (cache_grow(cache, flags, nid, obj)) {
+ if (cache_grow(cache, flags, nid, obj, pfmemalloc)) {
obj = ____cache_alloc_node(cache,
flags | GFP_THISNODE, nid);
if (!obj)
@@ -3360,7 +3507,7 @@ retry:
must_grow:
spin_unlock(&l3->list_lock);
- x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL);
+ x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL, false);
if (x)
goto retry;
@@ -3510,9 +3657,12 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
struct kmem_list3 *l3;
for (i = 0; i < nr_objects; i++) {
- void *objp = objpp[i];
+ void *objp;
struct slab *slabp;
+ clear_obj_pfmemalloc(&objpp[i]);
+ objp = objpp[i];
+
slabp = virt_to_slab(objp);
l3 = cachep->nodelists[node];
list_del(&slabp->list);
@@ -3624,12 +3774,12 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp)
if (likely(ac->avail < ac->limit)) {
STATS_INC_FREEHIT(cachep);
- ac->entry[ac->avail++] = objp;
+ ac_put_obj(cachep, ac, objp);
return;
} else {
STATS_INC_FREEMISS(cachep);
cache_flusharray(cachep, ac);
- ac->entry[ac->avail++] = objp;
+ ac_put_obj(cachep, ac, objp);
}
}
@@ -4061,7 +4211,7 @@ static void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
if (!ac || !ac->avail)
return;
if (ac->touched && !force) {
- ac->touched = 0;
+ ac->touched = false;
} else {
spin_lock_irq(&l3->list_lock);
if (ac->avail) {
diff --git a/mm/slub.c b/mm/slub.c
index e15aa7f..24aed12 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -30,6 +30,8 @@
#include <trace/events/kmem.h>
+#include "internal.h"
+
/*
* Lock order:
* 1. slab_lock(page)
@@ -1183,7 +1185,8 @@ static void setup_object(struct kmem_cache *s, struct page *page,
s->ctor(object);
}
-static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node,
+ bool *pfmemalloc)
{
struct page *page;
void *start;
@@ -1198,6 +1201,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
goto out;
inc_slabs_node(s, page_to_nid(page), page->objects);
+ *pfmemalloc = page->pfmemalloc;
page->slab = s;
page->flags |= 1 << PG_slab;
@@ -1629,6 +1633,16 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
}
}
+#define SLAB_PAGE_PFMEMALLOC 1
+
+static inline bool pfmemalloc_match(struct kmem_cache_cpu *c, gfp_t gfpflags)
+{
+ if (unlikely(c->pfmemalloc))
+ return gfp_pfmemalloc_allowed(gfpflags);
+
+ return true;
+}
+
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
@@ -1652,6 +1666,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
{
void **object;
struct page *new;
+ bool pfmemalloc = false;
/* We handle __GFP_ZERO in the caller */
gfpflags &= ~__GFP_ZERO;
@@ -1660,7 +1675,13 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
goto new_slab;
slab_lock(c->page);
- if (unlikely(!node_match(c, node)))
+
+ /*
+ * By rights, we should be searching for a slab page that was
+ * PFMEMALLOC but right now, we are losing the pfmemalloc
+ * information when the page leaves the per-cpu allocator
+ */
+ if (unlikely(!pfmemalloc_match(c, gfpflags) || !node_match(c, node)))
goto another_slab;
stat(s, ALLOC_REFILL);
@@ -1696,7 +1717,7 @@ new_slab:
if (gfpflags & __GFP_WAIT)
local_irq_enable();
- new = new_slab(s, gfpflags, node);
+ new = new_slab(s, gfpflags, node, &pfmemalloc);
if (gfpflags & __GFP_WAIT)
local_irq_disable();
@@ -1709,6 +1730,7 @@ new_slab:
slab_lock(new);
__SetPageSlubFrozen(new);
c->page = new;
+ c->pfmemalloc = pfmemalloc;
goto load_freelist;
}
if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
@@ -1747,8 +1769,8 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
local_irq_save(flags);
c = __this_cpu_ptr(s->cpu_slab);
object = c->freelist;
- if (unlikely(!object || !node_match(c, node)))
-
+ if (unlikely(!object || !node_match(c, node) ||
+ !pfmemalloc_match(c, gfpflags)))
object = __slab_alloc(s, gfpflags, node, addr, c);
else {
@@ -2131,10 +2153,11 @@ static void early_kmem_cache_node_alloc(int node)
struct page *page;
struct kmem_cache_node *n;
unsigned long flags;
+ bool pfmemalloc; /* Ignore this early in boot */
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
- page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
+ page = new_slab(kmem_cache_node, GFP_NOWAIT, node, &pfmemalloc);
BUG_ON(!page);
if (page_to_nid(page) != node) {
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 02/12] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Allocations of pages below the min watermark run a risk of the machine
hanging due to lack of memory. To prevent this, only callers who
have PF_MEMALLOC or TIF_MEMDIE set and not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated
to a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
Pages allocated from the reserve are returned with page->pfmemalloc
set and it's up to the caller to determine how the page should be
protected. SLAB restricts access to any page with page->pfmemalloc set
to callers which are known to able to access the PFMEMALLOC reserve. If
one is not available, an attempt is made to allocate a new page rather
than use a reserve. SLUB is a bit more relaxed in that it only records
if the current per-CPU page was allocated from PFMEMALLOC reserve and
uses another partial slab if the caller does not have the necessary
GFP or process flags. This was found to be sufficient in tests to
avoid hangs due to SLUB generally maintaining smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators
can fail a slab allocation even though free objects are available
because they are being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/mm_types.h | 8 ++
include/linux/slub_def.h | 1 +
mm/internal.h | 3 +
mm/page_alloc.c | 27 +++++-
mm/slab.c | 216 +++++++++++++++++++++++++++++++++++++++-------
mm/slub.c | 35 ++++++--
6 files changed, 246 insertions(+), 44 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 26bc4e2..1a5e14b 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -71,6 +71,14 @@ struct page {
union {
pgoff_t index; /* Our offset within mapping. */
void *freelist; /* SLUB: freelist req. slab lock */
+ bool pfmemalloc; /* If set by the page allocator,
+ * ALLOC_PFMEMALLOC was set and the
+ * low watermark was not met implying
+ * that the system is under some
+ * pressure. The caller should try
+ * ensure this page is only used to
+ * free other pages.
+ */
};
struct list_head lru; /* Pageout list, eg. active_list
* protected by zone->lru_lock !
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 8b6e8ae..f6cdbce 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -38,6 +38,7 @@ struct kmem_cache_cpu {
void **freelist; /* Pointer to first free per cpu object */
struct page *page; /* The slab from which we are allocating */
int node; /* The node of the page (or -1 for debug) */
+ bool pfmemalloc; /* Slab page had pfmemalloc set */
#ifdef CONFIG_SLUB_STATS
unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
diff --git a/mm/internal.h b/mm/internal.h
index 6948820..110c9a2 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -189,6 +189,9 @@ static inline struct page *mem_map_next(struct page *iter,
#define __paginginit __init
#endif
+/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
+
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 93afea3..fb34549 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -647,6 +647,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
trace_mm_page_free_direct(page, order);
kmemcheck_free_shadow(page, order);
+ page->pfmemalloc = false;
if (PageAnon(page))
page->mapping = NULL;
for (i = 0; i < (1 << order); i++)
@@ -1165,6 +1166,7 @@ void free_hot_cold_page(struct page *page, int cold)
migratetype = get_pageblock_migratetype(page);
set_page_private(page, migratetype);
+ page->pfmemalloc = false;
local_irq_save(flags);
if (unlikely(wasMlocked))
free_page_mlock(page);
@@ -1358,6 +1360,7 @@ failed:
#define ALLOC_HARDER 0x10 /* try to alloc harder */
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
+#define ALLOC_PFMEMALLOC 0x80 /* Caller has PF_MEMALLOC set */
#ifdef CONFIG_FAIL_PAGE_ALLOC
@@ -1979,16 +1982,22 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
} else if (unlikely(rt_task(current)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;
- if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
- if (!in_interrupt() &&
- ((current->flags & PF_MEMALLOC) ||
- unlikely(test_thread_flag(TIF_MEMDIE))))
+ if ((current->flags & PF_MEMALLOC) ||
+ unlikely(test_thread_flag(TIF_MEMDIE))) {
+ alloc_flags |= ALLOC_PFMEMALLOC;
+
+ if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
alloc_flags |= ALLOC_NO_WATERMARKS;
}
return alloc_flags;
}
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
+{
+ return gfp_to_alloc_flags(gfp_mask) & ALLOC_PFMEMALLOC;
+}
+
static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
@@ -2167,8 +2176,16 @@ nopage:
got_pg:
if (kmemcheck_enabled)
kmemcheck_pagealloc_alloc(page, order, gfp_mask);
- return page;
+ /*
+ * page->pfmemalloc is set when the caller had PFMEMALLOC set or is
+ * been OOM killed. The expectation is that the caller is taking
+ * steps that will free more memory. The caller should avoid the
+ * page being used for !PFMEMALLOC purposes.
+ */
+ page->pfmemalloc = (alloc_flags & ALLOC_PFMEMALLOC);
+
+ return page;
}
/*
diff --git a/mm/slab.c b/mm/slab.c
index 37961d1f..953e6263 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -120,6 +120,8 @@
#include <asm/tlbflush.h>
#include <asm/page.h>
+#include "internal.h"
+
/*
* DEBUG - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
* 0 for faster, smaller code (especially in the critical paths).
@@ -204,6 +206,7 @@ struct slab {
unsigned int inuse; /* num of objs active in slab */
kmem_bufctl_t free;
unsigned short nodeid;
+ bool pfmemalloc; /* Slab page had pfmemalloc set */
};
/*
@@ -244,15 +247,37 @@ struct array_cache {
unsigned int avail;
unsigned int limit;
unsigned int batchcount;
- unsigned int touched;
+ bool touched;
+ bool pfmemalloc;
spinlock_t lock;
void *entry[]; /*
* Must have this definition in here for the proper
* alignment of array_cache. Also simplifies accessing
* the entries.
+ *
+ * Entries should not be directly dereferenced as
+ * entries belonging to slabs marked pfmemalloc will
+ * have the lower bits set SLAB_OBJ_PFMEMALLOC
*/
};
+#define SLAB_OBJ_PFMEMALLOC 1
+static inline bool is_obj_pfmemalloc(void *objp)
+{
+ return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC;
+}
+
+static inline void set_obj_pfmemalloc(void **objp)
+{
+ *objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC);
+ return;
+}
+
+static inline void clear_obj_pfmemalloc(void **objp)
+{
+ *objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
+}
+
/*
* bootstrap: The caches do not work without cpuarrays anymore, but the
* cpuarrays are allocated from the generic caches...
@@ -885,12 +910,100 @@ static struct array_cache *alloc_arraycache(int node, int entries,
nc->avail = 0;
nc->limit = entries;
nc->batchcount = batchcount;
- nc->touched = 0;
+ nc->touched = false;
spin_lock_init(&nc->lock);
}
return nc;
}
+/* Clears ac->pfmemalloc if no slabs have pfmalloc set */
+static void check_ac_pfmemalloc(struct kmem_cache *cachep,
+ struct array_cache *ac)
+{
+ struct kmem_list3 *l3 = cachep->nodelists[numa_mem_id()];
+ struct slab *slabp;
+
+ if (!ac->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_full, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_partial, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ list_for_each_entry(slabp, &l3->slabs_free, list)
+ if (slabp->pfmemalloc)
+ return;
+
+ ac->pfmemalloc = false;
+}
+
+static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ gfp_t flags, bool force_refill)
+{
+ int i;
+ void *objp = ac->entry[--ac->avail];
+
+ /* Ensure the caller is allowed to use objects from PFMEMALLOC slab */
+ if (unlikely(is_obj_pfmemalloc(objp))) {
+ struct kmem_list3 *l3;
+
+ if (gfp_pfmemalloc_allowed(flags)) {
+ clear_obj_pfmemalloc(&objp);
+ return objp;
+ }
+
+ /* The caller cannot use PFMEMALLOC objects, find another one */
+ for (i = 1; i < ac->avail; i++) {
+ /* If a !PFMEMALLOC object is found, swap them */
+ if (!is_obj_pfmemalloc(ac->entry[i])) {
+ objp = ac->entry[i];
+ ac->entry[i] = ac->entry[ac->avail];
+ ac->entry[ac->avail] = objp;
+ return objp;
+ }
+ }
+
+ /*
+ * If there are full empty slabs and we were not forced to
+ * allocate a slab, mark this one !pfmemalloc
+ */
+ l3 = cachep->nodelists[numa_mem_id()];
+ if (!list_empty(&l3->slabs_free) && force_refill) {
+ struct slab *slabp = virt_to_slab(objp);
+ slabp->pfmemalloc = false;
+ clear_obj_pfmemalloc(&objp);
+ check_ac_pfmemalloc(cachep, ac);
+ return objp;
+ }
+
+ /* No !PFMEMALLOC objects available */
+ ac->avail++;
+ objp = NULL;
+ }
+
+ return objp;
+}
+
+static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ void *objp)
+{
+ struct slab *slabp;
+
+ /* If there are pfmemalloc slabs, check if the object is part of one */
+ if (unlikely(ac->pfmemalloc)) {
+ slabp = virt_to_slab(objp);
+
+ if (slabp->pfmemalloc)
+ set_obj_pfmemalloc(&objp);
+ }
+
+ ac->entry[ac->avail++] = objp;
+}
+
/*
* Transfer objects in one arraycache to another.
* Locking must be handled by the caller.
@@ -1067,7 +1180,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
STATS_INC_ACOVERFLOW(cachep);
__drain_alien_cache(cachep, alien, nodeid);
}
- alien->entry[alien->avail++] = objp;
+ ac_put_obj(cachep, alien, objp);
spin_unlock(&alien->lock);
} else {
spin_lock(&(cachep->nodelists[nodeid])->list_lock);
@@ -1674,7 +1787,8 @@ __initcall(cpucache_init);
* did not request dmaable memory, we might get it, but that
* would be relatively rare and ignorable.
*/
-static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
+static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid,
+ bool *pfmemalloc)
{
struct page *page;
int nr_pages;
@@ -1695,6 +1809,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
page = alloc_pages_exact_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder);
if (!page)
return NULL;
+ *pfmemalloc = page->pfmemalloc;
nr_pages = (1 << cachep->gfporder);
if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
@@ -2127,7 +2242,7 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
cpu_cache_get(cachep)->avail = 0;
cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
cpu_cache_get(cachep)->batchcount = 1;
- cpu_cache_get(cachep)->touched = 0;
+ cpu_cache_get(cachep)->touched = false;
cachep->batchcount = 1;
cachep->limit = BOOT_CPUCACHE_ENTRIES;
return 0;
@@ -2676,6 +2791,7 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
slabp->s_mem = objp + colour_off;
slabp->nodeid = nodeid;
slabp->free = 0;
+ slabp->pfmemalloc = false;
return slabp;
}
@@ -2807,7 +2923,7 @@ static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
* kmem_cache_alloc() when there are no active objs left in a cache.
*/
static int cache_grow(struct kmem_cache *cachep,
- gfp_t flags, int nodeid, void *objp)
+ gfp_t flags, int nodeid, void *objp, bool pfmemalloc)
{
struct slab *slabp;
size_t offset;
@@ -2851,7 +2967,7 @@ static int cache_grow(struct kmem_cache *cachep,
* 'nodeid'.
*/
if (!objp)
- objp = kmem_getpages(cachep, local_flags, nodeid);
+ objp = kmem_getpages(cachep, local_flags, nodeid, &pfmemalloc);
if (!objp)
goto failed;
@@ -2861,6 +2977,13 @@ static int cache_grow(struct kmem_cache *cachep,
if (!slabp)
goto opps1;
+ /* Record if ALLOC_PFMEMALLOC was set when allocating the slab */
+ if (pfmemalloc) {
+ struct array_cache *ac = cpu_cache_get(cachep);
+ slabp->pfmemalloc = true;
+ ac->pfmemalloc = 1;
+ }
+
slab_map_pages(cachep, slabp, objp);
cache_init_objs(cachep, slabp);
@@ -3002,16 +3125,19 @@ bad:
#define check_slabp(x,y) do { } while(0)
#endif
-static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
+static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags,
+ bool force_refill)
{
int batchcount;
struct kmem_list3 *l3;
struct array_cache *ac;
int node;
-retry:
check_irq_off();
node = numa_mem_id();
+ if (unlikely(force_refill))
+ goto force_grow;
+retry:
ac = cpu_cache_get(cachep);
batchcount = ac->batchcount;
if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
@@ -3029,7 +3155,7 @@ retry:
/* See if we can refill from the shared array */
if (l3->shared && transfer_objects(ac, l3->shared, batchcount)) {
- l3->shared->touched = 1;
+ l3->shared->touched = true;
goto alloc_done;
}
@@ -3061,8 +3187,8 @@ retry:
STATS_INC_ACTIVE(cachep);
STATS_SET_HIGH(cachep);
- ac->entry[ac->avail++] = slab_get_obj(cachep, slabp,
- node);
+ ac_put_obj(cachep, ac, slab_get_obj(cachep, slabp,
+ node));
}
check_slabp(cachep, slabp);
@@ -3081,18 +3207,25 @@ alloc_done:
if (unlikely(!ac->avail)) {
int x;
- x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL);
+force_grow:
+ x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL, false);
/* cache_grow can reenable interrupts, then ac could change. */
ac = cpu_cache_get(cachep);
- if (!x && ac->avail == 0) /* no objects in sight? abort */
+
+ /* no objects in sight? abort */
+ if (!x && (ac->avail == 0 || force_refill))
return NULL;
- if (!ac->avail) /* objects refilled by interrupt? */
+ /* objects refilled by interrupt? */
+ if (!ac->avail) {
+ node = numa_node_id();
goto retry;
+ }
}
- ac->touched = 1;
- return ac->entry[--ac->avail];
+ ac->touched = true;
+
+ return ac_get_obj(cachep, ac, flags, force_refill);
}
static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
@@ -3175,23 +3308,35 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
void *objp;
struct array_cache *ac;
+ bool force_refill = false;
check_irq_off();
ac = cpu_cache_get(cachep);
if (likely(ac->avail)) {
- STATS_INC_ALLOCHIT(cachep);
- ac->touched = 1;
- objp = ac->entry[--ac->avail];
- } else {
- STATS_INC_ALLOCMISS(cachep);
- objp = cache_alloc_refill(cachep, flags);
+ ac->touched = true;
+ objp = ac_get_obj(cachep, ac, flags, false);
+
/*
- * the 'ac' may be updated by cache_alloc_refill(),
- * and kmemleak_erase() requires its correct value.
+ * Allow for the possibility all avail objects are not allowed
+ * by the current flags
*/
- ac = cpu_cache_get(cachep);
+ if (objp) {
+ STATS_INC_ALLOCHIT(cachep);
+ goto out;
+ }
+ force_refill = true;
}
+
+ STATS_INC_ALLOCMISS(cachep);
+ objp = cache_alloc_refill(cachep, flags, force_refill);
+ /*
+ * the 'ac' may be updated by cache_alloc_refill(),
+ * and kmemleak_erase() requires its correct value.
+ */
+ ac = cpu_cache_get(cachep);
+
+out:
/*
* To avoid a false negative, if an object that is in one of the
* per-CPU caches is leaked, we need to make sure kmemleak doesn't
@@ -3244,6 +3389,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
enum zone_type high_zoneidx = gfp_zone(flags);
void *obj = NULL;
int nid;
+ bool pfmemalloc;
if (flags & __GFP_THISNODE)
return NULL;
@@ -3280,7 +3426,8 @@ retry:
if (local_flags & __GFP_WAIT)
local_irq_enable();
kmem_flagcheck(cache, flags);
- obj = kmem_getpages(cache, local_flags, numa_mem_id());
+ obj = kmem_getpages(cache, local_flags, numa_mem_id(),
+ &pfmemalloc);
if (local_flags & __GFP_WAIT)
local_irq_disable();
if (obj) {
@@ -3288,7 +3435,7 @@ retry:
* Insert into the appropriate per node queues
*/
nid = page_to_nid(virt_to_page(obj));
- if (cache_grow(cache, flags, nid, obj)) {
+ if (cache_grow(cache, flags, nid, obj, pfmemalloc)) {
obj = ____cache_alloc_node(cache,
flags | GFP_THISNODE, nid);
if (!obj)
@@ -3360,7 +3507,7 @@ retry:
must_grow:
spin_unlock(&l3->list_lock);
- x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL);
+ x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL, false);
if (x)
goto retry;
@@ -3510,9 +3657,12 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
struct kmem_list3 *l3;
for (i = 0; i < nr_objects; i++) {
- void *objp = objpp[i];
+ void *objp;
struct slab *slabp;
+ clear_obj_pfmemalloc(&objpp[i]);
+ objp = objpp[i];
+
slabp = virt_to_slab(objp);
l3 = cachep->nodelists[node];
list_del(&slabp->list);
@@ -3624,12 +3774,12 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp)
if (likely(ac->avail < ac->limit)) {
STATS_INC_FREEHIT(cachep);
- ac->entry[ac->avail++] = objp;
+ ac_put_obj(cachep, ac, objp);
return;
} else {
STATS_INC_FREEMISS(cachep);
cache_flusharray(cachep, ac);
- ac->entry[ac->avail++] = objp;
+ ac_put_obj(cachep, ac, objp);
}
}
@@ -4061,7 +4211,7 @@ static void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
if (!ac || !ac->avail)
return;
if (ac->touched && !force) {
- ac->touched = 0;
+ ac->touched = false;
} else {
spin_lock_irq(&l3->list_lock);
if (ac->avail) {
diff --git a/mm/slub.c b/mm/slub.c
index e15aa7f..24aed12 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -30,6 +30,8 @@
#include <trace/events/kmem.h>
+#include "internal.h"
+
/*
* Lock order:
* 1. slab_lock(page)
@@ -1183,7 +1185,8 @@ static void setup_object(struct kmem_cache *s, struct page *page,
s->ctor(object);
}
-static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node,
+ bool *pfmemalloc)
{
struct page *page;
void *start;
@@ -1198,6 +1201,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
goto out;
inc_slabs_node(s, page_to_nid(page), page->objects);
+ *pfmemalloc = page->pfmemalloc;
page->slab = s;
page->flags |= 1 << PG_slab;
@@ -1629,6 +1633,16 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
}
}
+#define SLAB_PAGE_PFMEMALLOC 1
+
+static inline bool pfmemalloc_match(struct kmem_cache_cpu *c, gfp_t gfpflags)
+{
+ if (unlikely(c->pfmemalloc))
+ return gfp_pfmemalloc_allowed(gfpflags);
+
+ return true;
+}
+
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
@@ -1652,6 +1666,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
{
void **object;
struct page *new;
+ bool pfmemalloc = false;
/* We handle __GFP_ZERO in the caller */
gfpflags &= ~__GFP_ZERO;
@@ -1660,7 +1675,13 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
goto new_slab;
slab_lock(c->page);
- if (unlikely(!node_match(c, node)))
+
+ /*
+ * By rights, we should be searching for a slab page that was
+ * PFMEMALLOC but right now, we are losing the pfmemalloc
+ * information when the page leaves the per-cpu allocator
+ */
+ if (unlikely(!pfmemalloc_match(c, gfpflags) || !node_match(c, node)))
goto another_slab;
stat(s, ALLOC_REFILL);
@@ -1696,7 +1717,7 @@ new_slab:
if (gfpflags & __GFP_WAIT)
local_irq_enable();
- new = new_slab(s, gfpflags, node);
+ new = new_slab(s, gfpflags, node, &pfmemalloc);
if (gfpflags & __GFP_WAIT)
local_irq_disable();
@@ -1709,6 +1730,7 @@ new_slab:
slab_lock(new);
__SetPageSlubFrozen(new);
c->page = new;
+ c->pfmemalloc = pfmemalloc;
goto load_freelist;
}
if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
@@ -1747,8 +1769,8 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
local_irq_save(flags);
c = __this_cpu_ptr(s->cpu_slab);
object = c->freelist;
- if (unlikely(!object || !node_match(c, node)))
-
+ if (unlikely(!object || !node_match(c, node) ||
+ !pfmemalloc_match(c, gfpflags)))
object = __slab_alloc(s, gfpflags, node, addr, c);
else {
@@ -2131,10 +2153,11 @@ static void early_kmem_cache_node_alloc(int node)
struct page *page;
struct kmem_cache_node *n;
unsigned long flags;
+ bool pfmemalloc; /* Ignore this early in boot */
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
- page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
+ page = new_slab(kmem_cache_node, GFP_NOWAIT, node, &pfmemalloc);
BUG_ON(!page);
if (page_to_nid(page) != node) {
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 03/12] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
__GFP_MEMALLOC will allow the allocation to disregard the watermarks,
much like PF_MEMALLOC. It allows one to pass along the memalloc state in
object related allocation flags as opposed to task related flags, such
as sk->sk_allocation. This removes the need for ALLOC_PFMEMALLOC as
callers using __GFP_MEMALLOC can get the ALLOC_NO_WATERMARK flag which
is now enough to identify allocations related to page reclaim.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/gfp.h | 4 +++-
include/linux/mm_types.h | 2 +-
mm/page_alloc.c | 14 ++++++--------
mm/slab.c | 2 +-
4 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index dca3176..d54eb02 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -23,6 +23,7 @@ struct vm_area_struct;
#define ___GFP_REPEAT 0x400u
#define ___GFP_NOFAIL 0x800u
#define ___GFP_NORETRY 0x1000u
+#define ___GFP_MEMALLOC 0x2000u
#define ___GFP_COMP 0x4000u
#define ___GFP_ZERO 0x8000u
#define ___GFP_NOMEMALLOC 0x10000u
@@ -74,6 +75,7 @@ struct vm_area_struct;
#define __GFP_REPEAT ((__force gfp_t)___GFP_REPEAT) /* See above */
#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) /* See above */
#define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) /* See above */
+#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves */
#define __GFP_COMP ((__force gfp_t)___GFP_COMP) /* Add compound page metadata */
#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) /* Return zeroed page on success */
#define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves */
@@ -125,7 +127,7 @@ struct vm_area_struct;
/* Control page allocator reclaim behavior */
#define GFP_RECLAIM_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
- __GFP_NORETRY|__GFP_NOMEMALLOC)
+ __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
/* Control slab gfp mask during early boot */
#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS))
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 1a5e14b..d166b21 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -72,7 +72,7 @@ struct page {
pgoff_t index; /* Our offset within mapping. */
void *freelist; /* SLUB: freelist req. slab lock */
bool pfmemalloc; /* If set by the page allocator,
- * ALLOC_PFMEMALLOC was set and the
+ * ALLOC_NO_WATERMARKS was set and the
* low watermark was not met implying
* that the system is under some
* pressure. The caller should try
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fb34549..2f897c3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1360,7 +1360,6 @@ failed:
#define ALLOC_HARDER 0x10 /* try to alloc harder */
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
-#define ALLOC_PFMEMALLOC 0x80 /* Caller has PF_MEMALLOC set */
#ifdef CONFIG_FAIL_PAGE_ALLOC
@@ -1982,11 +1981,10 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
} else if (unlikely(rt_task(current)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;
- if ((current->flags & PF_MEMALLOC) ||
- unlikely(test_thread_flag(TIF_MEMDIE))) {
- alloc_flags |= ALLOC_PFMEMALLOC;
-
- if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
+ if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
+ if (gfp_mask & __GFP_MEMALLOC)
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ else if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
alloc_flags |= ALLOC_NO_WATERMARKS;
}
@@ -1995,7 +1993,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
{
- return gfp_to_alloc_flags(gfp_mask) & ALLOC_PFMEMALLOC;
+ return gfp_to_alloc_flags(gfp_mask) & ALLOC_NO_WATERMARKS;
}
static inline struct page *
@@ -2183,7 +2181,7 @@ got_pg:
* steps that will free more memory. The caller should avoid the
* page being used for !PFMEMALLOC purposes.
*/
- page->pfmemalloc = (alloc_flags & ALLOC_PFMEMALLOC);
+ page->pfmemalloc = (alloc_flags & ALLOC_NO_WATERMARKS);
return page;
}
diff --git a/mm/slab.c b/mm/slab.c
index 953e6263..8f81d17 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2977,7 +2977,7 @@ static int cache_grow(struct kmem_cache *cachep,
if (!slabp)
goto opps1;
- /* Record if ALLOC_PFMEMALLOC was set when allocating the slab */
+ /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
if (pfmemalloc) {
struct array_cache *ac = cpu_cache_get(cachep);
slabp->pfmemalloc = true;
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 03/12] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
__GFP_MEMALLOC will allow the allocation to disregard the watermarks,
much like PF_MEMALLOC. It allows one to pass along the memalloc state in
object related allocation flags as opposed to task related flags, such
as sk->sk_allocation. This removes the need for ALLOC_PFMEMALLOC as
callers using __GFP_MEMALLOC can get the ALLOC_NO_WATERMARK flag which
is now enough to identify allocations related to page reclaim.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/gfp.h | 4 +++-
include/linux/mm_types.h | 2 +-
mm/page_alloc.c | 14 ++++++--------
mm/slab.c | 2 +-
4 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index dca3176..d54eb02 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -23,6 +23,7 @@ struct vm_area_struct;
#define ___GFP_REPEAT 0x400u
#define ___GFP_NOFAIL 0x800u
#define ___GFP_NORETRY 0x1000u
+#define ___GFP_MEMALLOC 0x2000u
#define ___GFP_COMP 0x4000u
#define ___GFP_ZERO 0x8000u
#define ___GFP_NOMEMALLOC 0x10000u
@@ -74,6 +75,7 @@ struct vm_area_struct;
#define __GFP_REPEAT ((__force gfp_t)___GFP_REPEAT) /* See above */
#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) /* See above */
#define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) /* See above */
+#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves */
#define __GFP_COMP ((__force gfp_t)___GFP_COMP) /* Add compound page metadata */
#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) /* Return zeroed page on success */
#define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves */
@@ -125,7 +127,7 @@ struct vm_area_struct;
/* Control page allocator reclaim behavior */
#define GFP_RECLAIM_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
- __GFP_NORETRY|__GFP_NOMEMALLOC)
+ __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
/* Control slab gfp mask during early boot */
#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS))
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 1a5e14b..d166b21 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -72,7 +72,7 @@ struct page {
pgoff_t index; /* Our offset within mapping. */
void *freelist; /* SLUB: freelist req. slab lock */
bool pfmemalloc; /* If set by the page allocator,
- * ALLOC_PFMEMALLOC was set and the
+ * ALLOC_NO_WATERMARKS was set and the
* low watermark was not met implying
* that the system is under some
* pressure. The caller should try
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fb34549..2f897c3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1360,7 +1360,6 @@ failed:
#define ALLOC_HARDER 0x10 /* try to alloc harder */
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
-#define ALLOC_PFMEMALLOC 0x80 /* Caller has PF_MEMALLOC set */
#ifdef CONFIG_FAIL_PAGE_ALLOC
@@ -1982,11 +1981,10 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
} else if (unlikely(rt_task(current)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;
- if ((current->flags & PF_MEMALLOC) ||
- unlikely(test_thread_flag(TIF_MEMDIE))) {
- alloc_flags |= ALLOC_PFMEMALLOC;
-
- if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
+ if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
+ if (gfp_mask & __GFP_MEMALLOC)
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ else if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
alloc_flags |= ALLOC_NO_WATERMARKS;
}
@@ -1995,7 +1993,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
{
- return gfp_to_alloc_flags(gfp_mask) & ALLOC_PFMEMALLOC;
+ return gfp_to_alloc_flags(gfp_mask) & ALLOC_NO_WATERMARKS;
}
static inline struct page *
@@ -2183,7 +2181,7 @@ got_pg:
* steps that will free more memory. The caller should avoid the
* page being used for !PFMEMALLOC purposes.
*/
- page->pfmemalloc = (alloc_flags & ALLOC_PFMEMALLOC);
+ page->pfmemalloc = (alloc_flags & ALLOC_NO_WATERMARKS);
return page;
}
diff --git a/mm/slab.c b/mm/slab.c
index 953e6263..8f81d17 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2977,7 +2977,7 @@ static int cache_grow(struct kmem_cache *cachep,
if (!slabp)
goto opps1;
- /* Record if ALLOC_PFMEMALLOC was set when allocating the slab */
+ /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
if (pfmemalloc) {
struct array_cache *ac = cpu_cache_get(cachep);
slabp->pfmemalloc = true;
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 04/12] mm: allow PF_MEMALLOC from softirq context
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
This is needed to allow network softirq packet processing to make use
of PF_MEMALLOC.
Currently softirq context cannot use PF_MEMALLOC due to it not being
associated with a task, and therefore not having task flags to fiddle with -
thus the gfp to alloc flag mapping ignores the task flags when in interrupts
(hard or soft) context.
Allowing softirqs to make use of PF_MEMALLOC therefore requires some trickery.
We basically borrow the task flags from whatever process happens to be
preempted by the softirq.
So we modify the gfp to alloc flags mapping to not exclude task flags in
softirq context, and modify the softirq code to save, clear and restore
the PF_MEMALLOC flag.
The save and clear, ensures the preempted task's PF_MEMALLOC flag doesn't
leak into the softirq. The restore ensures a softirq's PF_MEMALLOC flag
cannot leak back into the preempted process.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/sched.h | 7 +++++++
kernel/softirq.c | 3 +++
mm/page_alloc.c | 5 ++++-
3 files changed, 14 insertions(+), 1 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 777d8a5..b753de6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1799,6 +1799,13 @@ static inline void rcu_copy_process(struct task_struct *p)
#endif
+static inline void tsk_restore_flags(struct task_struct *p,
+ unsigned long pflags, unsigned long mask)
+{
+ p->flags &= ~mask;
+ p->flags |= pflags & mask;
+}
+
#ifdef CONFIG_SMP
extern int set_cpus_allowed_ptr(struct task_struct *p,
const struct cpumask *new_mask);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 68eb5ef..cfa9ba4 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -210,6 +210,8 @@ asmlinkage void __do_softirq(void)
__u32 pending;
int max_restart = MAX_SOFTIRQ_RESTART;
int cpu;
+ unsigned long pflags = current->flags;
+ current->flags &= ~PF_MEMALLOC;
pending = local_softirq_pending();
account_system_vtime(current);
@@ -265,6 +267,7 @@ restart:
account_system_vtime(current);
__local_bh_enable(SOFTIRQ_OFFSET);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
}
#ifndef __ARCH_HAS_DO_SOFTIRQ
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2f897c3..8318cf2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1984,7 +1984,10 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
if (gfp_mask & __GFP_MEMALLOC)
alloc_flags |= ALLOC_NO_WATERMARKS;
- else if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
+ else if (!in_irq() && (current->flags & PF_MEMALLOC))
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ else if (!in_interrupt() &&
+ unlikely(test_thread_flag(TIF_MEMDIE)))
alloc_flags |= ALLOC_NO_WATERMARKS;
}
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 04/12] mm: allow PF_MEMALLOC from softirq context
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
This is needed to allow network softirq packet processing to make use
of PF_MEMALLOC.
Currently softirq context cannot use PF_MEMALLOC due to it not being
associated with a task, and therefore not having task flags to fiddle with -
thus the gfp to alloc flag mapping ignores the task flags when in interrupts
(hard or soft) context.
Allowing softirqs to make use of PF_MEMALLOC therefore requires some trickery.
We basically borrow the task flags from whatever process happens to be
preempted by the softirq.
So we modify the gfp to alloc flags mapping to not exclude task flags in
softirq context, and modify the softirq code to save, clear and restore
the PF_MEMALLOC flag.
The save and clear, ensures the preempted task's PF_MEMALLOC flag doesn't
leak into the softirq. The restore ensures a softirq's PF_MEMALLOC flag
cannot leak back into the preempted process.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/sched.h | 7 +++++++
kernel/softirq.c | 3 +++
mm/page_alloc.c | 5 ++++-
3 files changed, 14 insertions(+), 1 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 777d8a5..b753de6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1799,6 +1799,13 @@ static inline void rcu_copy_process(struct task_struct *p)
#endif
+static inline void tsk_restore_flags(struct task_struct *p,
+ unsigned long pflags, unsigned long mask)
+{
+ p->flags &= ~mask;
+ p->flags |= pflags & mask;
+}
+
#ifdef CONFIG_SMP
extern int set_cpus_allowed_ptr(struct task_struct *p,
const struct cpumask *new_mask);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 68eb5ef..cfa9ba4 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -210,6 +210,8 @@ asmlinkage void __do_softirq(void)
__u32 pending;
int max_restart = MAX_SOFTIRQ_RESTART;
int cpu;
+ unsigned long pflags = current->flags;
+ current->flags &= ~PF_MEMALLOC;
pending = local_softirq_pending();
account_system_vtime(current);
@@ -265,6 +267,7 @@ restart:
account_system_vtime(current);
__local_bh_enable(SOFTIRQ_OFFSET);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
}
#ifndef __ARCH_HAS_DO_SOFTIRQ
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2f897c3..8318cf2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1984,7 +1984,10 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
if (gfp_mask & __GFP_MEMALLOC)
alloc_flags |= ALLOC_NO_WATERMARKS;
- else if (likely(!(gfp_mask & __GFP_NOMEMALLOC)) && !in_interrupt())
+ else if (!in_irq() && (current->flags & PF_MEMALLOC))
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ else if (!in_interrupt() &&
+ unlikely(test_thread_flag(TIF_MEMDIE)))
alloc_flags |= ALLOC_NO_WATERMARKS;
}
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 05/12] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
The reserve is proportionally distributed over all !highmem zones in the
system. So we need to allow an emergency allocation access to all zones.
In order to do that we need to break out of any mempolicy boundaries we
might have.
In my opinion that does not break mempolicies as those are user oriented
and not system oriented. That is, system allocations are not guaranteed to
be within mempolicy boundaries. For instance IRQs don't even have a mempolicy.
So breaking out of mempolicy boundaries for 'rare' emergency allocations,
which are always system allocations (as opposed to user) is ok.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/page_alloc.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8318cf2..2b87dfd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2064,6 +2064,13 @@ restart:
rebalance:
/* Allocate without watermarks if the context allows */
if (alloc_flags & ALLOC_NO_WATERMARKS) {
+ /*
+ * Ignore mempolicies if ALLOC_NO_WATERMARKS on the grounds
+ * the allocation is high priority and these type of
+ * allocations are system rather than user orientated
+ */
+ zonelist = node_zonelist(numa_node_id(), gfp_mask);
+
page = __alloc_pages_high_priority(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
preferred_zone, migratetype);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 05/12] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
The reserve is proportionally distributed over all !highmem zones in the
system. So we need to allow an emergency allocation access to all zones.
In order to do that we need to break out of any mempolicy boundaries we
might have.
In my opinion that does not break mempolicies as those are user oriented
and not system oriented. That is, system allocations are not guaranteed to
be within mempolicy boundaries. For instance IRQs don't even have a mempolicy.
So breaking out of mempolicy boundaries for 'rare' emergency allocations,
which are always system allocations (as opposed to user) is ok.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/page_alloc.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8318cf2..2b87dfd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2064,6 +2064,13 @@ restart:
rebalance:
/* Allocate without watermarks if the context allows */
if (alloc_flags & ALLOC_NO_WATERMARKS) {
+ /*
+ * Ignore mempolicies if ALLOC_NO_WATERMARKS on the grounds
+ * the allocation is high priority and these type of
+ * allocations are system rather than user orientated
+ */
+ zonelist = node_zonelist(numa_node_id(), gfp_mask);
+
page = __alloc_pages_high_priority(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
preferred_zone, migratetype);
--
1.7.3.4
--
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the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 06/12] net: Introduce sk_allocation() to allow addition of GFP flags depending on the individual socket
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Introduce sk_allocation(), this function allows to inject sock specific
flags to each sock related allocation. It is only used on allocation
paths that may be required for writing pages back to network storage.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 +++++
net/ipv4/tcp.c | 3 ++-
net/ipv4/tcp_output.c | 13 +++++++------
net/ipv6/tcp_ipv6.c | 12 +++++++++---
4 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index bc1cf7d8..f687e0b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -584,6 +584,11 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
return test_bit(flag, &sk->sk_flags);
}
+static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
+{
+ return gfp_mask;
+}
+
static inline void sk_acceptq_removed(struct sock *sk)
{
sk->sk_ack_backlog--;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6c11eec..8939804 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -689,7 +689,8 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
/* The TCP header must be at least 32-bit aligned. */
size = ALIGN(size, 4);
- skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
+ skb = alloc_skb_fclone(size + sk->sk_prot->max_header,
+ sk_allocation(sk, gfp));
if (skb) {
if (sk_wmem_schedule(sk, skb->truesize)) {
/*
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index dfa5beb..550c701 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2323,7 +2323,7 @@ void tcp_send_fin(struct sock *sk)
/* Socket is locked, keep trying until memory is available. */
for (;;) {
skb = alloc_skb_fclone(MAX_TCP_HEADER,
- sk->sk_allocation);
+ sk_allocation(sk, GFP_KERNEL));
if (skb)
break;
yield();
@@ -2349,7 +2349,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority)
struct sk_buff *skb;
/* NOTE: No TCP options attached and we never retransmit this. */
- skb = alloc_skb(MAX_TCP_HEADER, priority);
+ skb = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, priority));
if (!skb) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
return;
@@ -2422,7 +2422,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired)
s_data_desired = cvp->s_data_desired;
- skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC);
+ skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1,
+ sk_allocation(sk, GFP_ATOMIC));
if (skb == NULL)
return NULL;
@@ -2718,7 +2719,7 @@ void tcp_send_ack(struct sock *sk)
* tcp_transmit_skb() will set the ownership to this
* sock.
*/
- buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+ buff = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, GFP_ATOMIC));
if (buff == NULL) {
inet_csk_schedule_ack(sk);
inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
@@ -2733,7 +2734,7 @@ void tcp_send_ack(struct sock *sk)
/* Send it off, this clears delayed acks for us. */
TCP_SKB_CB(buff)->when = tcp_time_stamp;
- tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);
+ tcp_transmit_skb(sk, buff, 0, sk_allocation(sk, GFP_ATOMIC));
}
/* This routine sends a packet with an out of date sequence
@@ -2753,7 +2754,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
struct sk_buff *skb;
/* We don't queue it, tcp_transmit_skb() sets ownership. */
- skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+ skb = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, GFP_ATOMIC));
if (skb == NULL)
return -1;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 20aa95e..3a555de 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -610,7 +610,8 @@ static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
} else {
/* reallocate new list if current one is full. */
if (!tp->md5sig_info) {
- tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info), GFP_ATOMIC);
+ tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
+ sk_allocation(sk, GFP_ATOMIC));
if (!tp->md5sig_info) {
kfree(newkey);
return -ENOMEM;
@@ -623,7 +624,8 @@ static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
}
if (tp->md5sig_info->alloced6 == tp->md5sig_info->entries6) {
keys = kmalloc((sizeof (tp->md5sig_info->keys6[0]) *
- (tp->md5sig_info->entries6 + 1)), GFP_ATOMIC);
+ (tp->md5sig_info->entries6 + 1)),
+ sk_allocation(sk, GFP_ATOMIC));
if (!keys) {
tcp_free_md5sig_pool();
@@ -747,7 +749,8 @@ static int tcp_v6_parse_md5_keys (struct sock *sk, char __user *optval,
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_md5sig_info *p;
- p = kzalloc(sizeof(struct tcp_md5sig_info), GFP_KERNEL);
+ p = kzalloc(sizeof(struct tcp_md5sig_info),
+ sk_allocation(sk, GFP_KERNEL));
if (!p)
return -ENOMEM;
@@ -1098,6 +1101,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
struct tcphdr *th = tcp_hdr(skb);
u32 seq = 0, ack_seq = 0;
struct tcp_md5sig_key *key = NULL;
+ gfp_t gfp_mask = GFP_ATOMIC;
if (th->rst)
return;
@@ -1109,6 +1113,8 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
if (sk)
key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr);
#endif
+ if (sk)
+ gfp_mask = sk_allocation(sk, gfp_mask);
if (th->ack)
seq = ntohl(th->ack_seq);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 06/12] net: Introduce sk_allocation() to allow addition of GFP flags depending on the individual socket
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Introduce sk_allocation(), this function allows to inject sock specific
flags to each sock related allocation. It is only used on allocation
paths that may be required for writing pages back to network storage.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 +++++
net/ipv4/tcp.c | 3 ++-
net/ipv4/tcp_output.c | 13 +++++++------
net/ipv6/tcp_ipv6.c | 12 +++++++++---
4 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index bc1cf7d8..f687e0b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -584,6 +584,11 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
return test_bit(flag, &sk->sk_flags);
}
+static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
+{
+ return gfp_mask;
+}
+
static inline void sk_acceptq_removed(struct sock *sk)
{
sk->sk_ack_backlog--;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6c11eec..8939804 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -689,7 +689,8 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
/* The TCP header must be at least 32-bit aligned. */
size = ALIGN(size, 4);
- skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
+ skb = alloc_skb_fclone(size + sk->sk_prot->max_header,
+ sk_allocation(sk, gfp));
if (skb) {
if (sk_wmem_schedule(sk, skb->truesize)) {
/*
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index dfa5beb..550c701 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2323,7 +2323,7 @@ void tcp_send_fin(struct sock *sk)
/* Socket is locked, keep trying until memory is available. */
for (;;) {
skb = alloc_skb_fclone(MAX_TCP_HEADER,
- sk->sk_allocation);
+ sk_allocation(sk, GFP_KERNEL));
if (skb)
break;
yield();
@@ -2349,7 +2349,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority)
struct sk_buff *skb;
/* NOTE: No TCP options attached and we never retransmit this. */
- skb = alloc_skb(MAX_TCP_HEADER, priority);
+ skb = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, priority));
if (!skb) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
return;
@@ -2422,7 +2422,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired)
s_data_desired = cvp->s_data_desired;
- skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC);
+ skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1,
+ sk_allocation(sk, GFP_ATOMIC));
if (skb == NULL)
return NULL;
@@ -2718,7 +2719,7 @@ void tcp_send_ack(struct sock *sk)
* tcp_transmit_skb() will set the ownership to this
* sock.
*/
- buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+ buff = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, GFP_ATOMIC));
if (buff == NULL) {
inet_csk_schedule_ack(sk);
inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
@@ -2733,7 +2734,7 @@ void tcp_send_ack(struct sock *sk)
/* Send it off, this clears delayed acks for us. */
TCP_SKB_CB(buff)->when = tcp_time_stamp;
- tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);
+ tcp_transmit_skb(sk, buff, 0, sk_allocation(sk, GFP_ATOMIC));
}
/* This routine sends a packet with an out of date sequence
@@ -2753,7 +2754,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
struct sk_buff *skb;
/* We don't queue it, tcp_transmit_skb() sets ownership. */
- skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+ skb = alloc_skb(MAX_TCP_HEADER, sk_allocation(sk, GFP_ATOMIC));
if (skb == NULL)
return -1;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 20aa95e..3a555de 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -610,7 +610,8 @@ static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
} else {
/* reallocate new list if current one is full. */
if (!tp->md5sig_info) {
- tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info), GFP_ATOMIC);
+ tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
+ sk_allocation(sk, GFP_ATOMIC));
if (!tp->md5sig_info) {
kfree(newkey);
return -ENOMEM;
@@ -623,7 +624,8 @@ static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
}
if (tp->md5sig_info->alloced6 == tp->md5sig_info->entries6) {
keys = kmalloc((sizeof (tp->md5sig_info->keys6[0]) *
- (tp->md5sig_info->entries6 + 1)), GFP_ATOMIC);
+ (tp->md5sig_info->entries6 + 1)),
+ sk_allocation(sk, GFP_ATOMIC));
if (!keys) {
tcp_free_md5sig_pool();
@@ -747,7 +749,8 @@ static int tcp_v6_parse_md5_keys (struct sock *sk, char __user *optval,
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_md5sig_info *p;
- p = kzalloc(sizeof(struct tcp_md5sig_info), GFP_KERNEL);
+ p = kzalloc(sizeof(struct tcp_md5sig_info),
+ sk_allocation(sk, GFP_KERNEL));
if (!p)
return -ENOMEM;
@@ -1098,6 +1101,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
struct tcphdr *th = tcp_hdr(skb);
u32 seq = 0, ack_seq = 0;
struct tcp_md5sig_key *key = NULL;
+ gfp_t gfp_mask = GFP_ATOMIC;
if (th->rst)
return;
@@ -1109,6 +1113,8 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
if (sk)
key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr);
#endif
+ if (sk)
+ gfp_mask = sk_allocation(sk, gfp_mask);
if (th->ack)
seq = ntohl(th->ack_seq);
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 07/12] netvm: Allow the use of __GFP_MEMALLOC by specific sockets
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Allow specific sockets to be tagged SOCK_MEMALLOC and use __GFP_MEMALLOC
for their allocations. These sockets will be able to go below watermarks
and allocate from the emergency reserve. Such sockets are to be used
to service the VM (iow. to swap over). They must be handled kernel side,
exposing such a socket to user-space is a bug.
There is a risk that the reserves be depleted so for now, the administrator is
responsible for increasing min_free_kbytes as necessary to prevent deadlock
for their workloads.
[a.p.zijlstra@chello.nl: Original patches]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 ++++-
net/core/sock.c | 22 ++++++++++++++++++++++
2 files changed, 26 insertions(+), 1 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index f687e0b..e6ead99 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -553,6 +553,7 @@ enum sock_flags {
SOCK_RCVTSTAMPNS, /* %SO_TIMESTAMPNS setting */
SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
SOCK_QUEUE_SHRUNK, /* write queue has been shrunk recently */
+ SOCK_MEMALLOC, /* VM depends on this socket for swapping */
SOCK_TIMESTAMPING_TX_HARDWARE, /* %SOF_TIMESTAMPING_TX_HARDWARE */
SOCK_TIMESTAMPING_TX_SOFTWARE, /* %SOF_TIMESTAMPING_TX_SOFTWARE */
SOCK_TIMESTAMPING_RX_HARDWARE, /* %SOF_TIMESTAMPING_RX_HARDWARE */
@@ -586,7 +587,7 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
{
- return gfp_mask;
+ return gfp_mask | (sk->sk_allocation & __GFP_MEMALLOC);
}
static inline void sk_acceptq_removed(struct sock *sk)
@@ -716,6 +717,8 @@ extern int sk_stream_wait_memory(struct sock *sk, long *timeo_p);
extern void sk_stream_wait_close(struct sock *sk, long timeo_p);
extern int sk_stream_error(struct sock *sk, int flags, int err);
extern void sk_stream_kill_queues(struct sock *sk);
+extern void sk_set_memalloc(struct sock *sk);
+extern void sk_clear_memalloc(struct sock *sk);
extern int sk_wait_data(struct sock *sk, long *timeo);
diff --git a/net/core/sock.c b/net/core/sock.c
index 7dfed79..1deb48b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -219,6 +219,28 @@ __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
EXPORT_SYMBOL(sysctl_optmem_max);
+/**
+ * sk_set_memalloc - sets %SOCK_MEMALLOC
+ * @sk: socket to set it on
+ *
+ * Set %SOCK_MEMALLOC on a socket for access to emergency reserves.
+ * It's the responsibility of the admin to adjust min_free_kbytes
+ * to meet the requirements
+ */
+void sk_set_memalloc(struct sock *sk)
+{
+ sock_set_flag(sk, SOCK_MEMALLOC);
+ sk->sk_allocation |= __GFP_MEMALLOC;
+}
+EXPORT_SYMBOL_GPL(sk_set_memalloc);
+
+void sk_clear_memalloc(struct sock *sk)
+{
+ sock_reset_flag(sk, SOCK_MEMALLOC);
+ sk->sk_allocation &= ~__GFP_MEMALLOC;
+}
+EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+
#if defined(CONFIG_CGROUPS) && !defined(CONFIG_NET_CLS_CGROUP)
int net_cls_subsys_id = -1;
EXPORT_SYMBOL_GPL(net_cls_subsys_id);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 07/12] netvm: Allow the use of __GFP_MEMALLOC by specific sockets
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Allow specific sockets to be tagged SOCK_MEMALLOC and use __GFP_MEMALLOC
for their allocations. These sockets will be able to go below watermarks
and allocate from the emergency reserve. Such sockets are to be used
to service the VM (iow. to swap over). They must be handled kernel side,
exposing such a socket to user-space is a bug.
There is a risk that the reserves be depleted so for now, the administrator is
responsible for increasing min_free_kbytes as necessary to prevent deadlock
for their workloads.
[a.p.zijlstra@chello.nl: Original patches]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 ++++-
net/core/sock.c | 22 ++++++++++++++++++++++
2 files changed, 26 insertions(+), 1 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index f687e0b..e6ead99 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -553,6 +553,7 @@ enum sock_flags {
SOCK_RCVTSTAMPNS, /* %SO_TIMESTAMPNS setting */
SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
SOCK_QUEUE_SHRUNK, /* write queue has been shrunk recently */
+ SOCK_MEMALLOC, /* VM depends on this socket for swapping */
SOCK_TIMESTAMPING_TX_HARDWARE, /* %SOF_TIMESTAMPING_TX_HARDWARE */
SOCK_TIMESTAMPING_TX_SOFTWARE, /* %SOF_TIMESTAMPING_TX_SOFTWARE */
SOCK_TIMESTAMPING_RX_HARDWARE, /* %SOF_TIMESTAMPING_RX_HARDWARE */
@@ -586,7 +587,7 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
{
- return gfp_mask;
+ return gfp_mask | (sk->sk_allocation & __GFP_MEMALLOC);
}
static inline void sk_acceptq_removed(struct sock *sk)
@@ -716,6 +717,8 @@ extern int sk_stream_wait_memory(struct sock *sk, long *timeo_p);
extern void sk_stream_wait_close(struct sock *sk, long timeo_p);
extern int sk_stream_error(struct sock *sk, int flags, int err);
extern void sk_stream_kill_queues(struct sock *sk);
+extern void sk_set_memalloc(struct sock *sk);
+extern void sk_clear_memalloc(struct sock *sk);
extern int sk_wait_data(struct sock *sk, long *timeo);
diff --git a/net/core/sock.c b/net/core/sock.c
index 7dfed79..1deb48b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -219,6 +219,28 @@ __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
EXPORT_SYMBOL(sysctl_optmem_max);
+/**
+ * sk_set_memalloc - sets %SOCK_MEMALLOC
+ * @sk: socket to set it on
+ *
+ * Set %SOCK_MEMALLOC on a socket for access to emergency reserves.
+ * It's the responsibility of the admin to adjust min_free_kbytes
+ * to meet the requirements
+ */
+void sk_set_memalloc(struct sock *sk)
+{
+ sock_set_flag(sk, SOCK_MEMALLOC);
+ sk->sk_allocation |= __GFP_MEMALLOC;
+}
+EXPORT_SYMBOL_GPL(sk_set_memalloc);
+
+void sk_clear_memalloc(struct sock *sk)
+{
+ sock_reset_flag(sk, SOCK_MEMALLOC);
+ sk->sk_allocation &= ~__GFP_MEMALLOC;
+}
+EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+
#if defined(CONFIG_CGROUPS) && !defined(CONFIG_NET_CLS_CGROUP)
int net_cls_subsys_id = -1;
EXPORT_SYMBOL_GPL(net_cls_subsys_id);
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Change the skb allocation API to indicate RX usage and use this to fall back
to the PFMEMALLOC reserve when needed. SKBs allocated from the reserve are
tagged in skb->pfmemalloc. If an SKB is allocated from the reserve and
the socket is later found to be unrelated to page reclaim, the packet is
dropped so that the memory remains available for page reclaim. Network
protocols are expected to recover from this packet loss.
[a.p.zijlstra@chello.nl: Ideas taken from various patches]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/gfp.h | 3 ++
include/linux/skbuff.h | 19 ++++++++--
include/net/sock.h | 6 +++
mm/internal.h | 3 --
net/core/filter.c | 8 ++++
net/core/skbuff.c | 95 ++++++++++++++++++++++++++++++++++++++++--------
net/core/sock.c | 9 +++++
7 files changed, 121 insertions(+), 22 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index d54eb02..ebf4d4f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -374,6 +374,9 @@ void drain_local_pages(void *dummy);
extern gfp_t gfp_allowed_mask;
+/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
+
extern void pm_restrict_gfp_mask(void);
extern void pm_restore_gfp_mask(void);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bf221d6..5cd4d23 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -393,6 +393,7 @@ struct sk_buff {
#else
__u8 deliver_no_wcard:1;
#endif
+ __u8 pfmemalloc:1;
__u8 ooo_okay:1;
kmemcheck_bitfield_end(flags2);
@@ -431,6 +432,15 @@ struct sk_buff {
#include <asm/system.h>
+#define SKB_ALLOC_FCLONE 0x01
+#define SKB_ALLOC_RX 0x02
+
+/* Returns true if the skb was allocated from PFMEMALLOC reserves */
+static inline bool skb_pfmemalloc(struct sk_buff *skb)
+{
+ return unlikely(skb->pfmemalloc);
+}
+
/*
* skb might have a dst pointer attached, refcounted or not.
* _skb_refdst low order bit is set if refcount was _not_ taken
@@ -488,7 +498,7 @@ extern void kfree_skb(struct sk_buff *skb);
extern void consume_skb(struct sk_buff *skb);
extern void __kfree_skb(struct sk_buff *skb);
extern struct sk_buff *__alloc_skb(unsigned int size,
- gfp_t priority, int fclone, int node);
+ gfp_t priority, int flags, int node);
static inline struct sk_buff *alloc_skb(unsigned int size,
gfp_t priority)
{
@@ -498,7 +508,7 @@ static inline struct sk_buff *alloc_skb(unsigned int size,
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
gfp_t priority)
{
- return __alloc_skb(size, priority, 1, NUMA_NO_NODE);
+ return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
}
extern bool skb_recycle_check(struct sk_buff *skb, int skb_size);
@@ -1524,7 +1534,8 @@ static inline void __skb_queue_purge(struct sk_buff_head *list)
static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
gfp_t gfp_mask)
{
- struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
+ struct sk_buff *skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask,
+ SKB_ALLOC_RX, NUMA_NO_NODE);
if (likely(skb))
skb_reserve(skb, NET_SKB_PAD);
return skb;
@@ -1575,7 +1586,7 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
*/
static inline struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask)
{
- return alloc_pages_node(NUMA_NO_NODE, gfp_mask, 0);
+ return alloc_pages_node(NUMA_NO_NODE, gfp_mask | __GFP_MEMALLOC, 0);
}
/**
diff --git a/include/net/sock.h b/include/net/sock.h
index e6ead99..1d8a26b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -585,6 +585,12 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
return test_bit(flag, &sk->sk_flags);
}
+extern int memalloc_socks;
+static inline int sk_memalloc_socks(void)
+{
+ return memalloc_socks;
+}
+
static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
{
return gfp_mask | (sk->sk_allocation & __GFP_MEMALLOC);
diff --git a/mm/internal.h b/mm/internal.h
index 110c9a2..6948820 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -189,9 +189,6 @@ static inline struct page *mem_map_next(struct page *iter,
#define __paginginit __init
#endif
-/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
-bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
-
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
diff --git a/net/core/filter.c b/net/core/filter.c
index afc5837..5223b48 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -138,6 +138,14 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
int err;
struct sk_filter *filter;
+ /*
+ * If the skb was allocated from pfmemalloc reserves, only
+ * allow SOCK_MEMALLOC sockets to use it as this socket is
+ * helping free memory
+ */
+ if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
+ return -ENOMEM;
+
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d883dcc..f3702ae 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -146,6 +146,43 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
BUG();
}
+
+/*
+ * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
+ * the caller if emergency pfmemalloc reserves are being used. If it is and
+ * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
+ * may be used. Otherwise, the packet data may be discarded until enough
+ * memory is free
+ */
+#define kmalloc_reserve(size, gfp, node, pfmemalloc) \
+ __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
+void *__kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip,
+ bool *pfmemalloc)
+{
+ void *obj;
+ bool ret_pfmemalloc = false;
+
+ /*
+ * Try a regular allocation, when that fails and we're not entitled
+ * to the reserves, fail.
+ */
+ obj = kmalloc_node_track_caller(size,
+ flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
+ node);
+ if (obj || !(gfp_pfmemalloc_allowed(flags)))
+ goto out;
+
+ /* Try again but now we are using pfmemalloc reserves */
+ ret_pfmemalloc = true;
+ obj = kmalloc_node_track_caller(size, flags, node);
+
+out:
+ if (pfmemalloc)
+ *pfmemalloc = ret_pfmemalloc;
+
+ return obj;
+}
+
/* Allocate a new skbuff. We do this ourselves so we can fill in a few
* 'private' fields and also do memory statistics to find all the
* [BEEP] leaks.
@@ -156,8 +193,10 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
* __alloc_skb - allocate a network buffer
* @size: size to allocate
* @gfp_mask: allocation mask
- * @fclone: allocate from fclone cache instead of head cache
- * and allocate a cloned (child) skb
+ * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
+ * instead of head cache and allocate a cloned (child) skb.
+ * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
+ * allocations in case the data is required for writeback
* @node: numa node to allocate memory on
*
* Allocate a new &sk_buff. The returned buffer has no headroom and a
@@ -168,14 +207,19 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
* %GFP_ATOMIC.
*/
struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
- int fclone, int node)
+ int flags, int node)
{
struct kmem_cache *cache;
struct skb_shared_info *shinfo;
struct sk_buff *skb;
u8 *data;
+ bool pfmemalloc;
+
+ cache = (flags & SKB_ALLOC_FCLONE)
+ ? skbuff_fclone_cache : skbuff_head_cache;
- cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
+ if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
+ gfp_mask |= __GFP_MEMALLOC;
/* Get the HEAD */
skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
@@ -184,8 +228,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
prefetchw(skb);
size = SKB_DATA_ALIGN(size);
- data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
- gfp_mask, node);
+ data = kmalloc_reserve(size + sizeof(struct skb_shared_info),
+ gfp_mask, node, &pfmemalloc);
if (!data)
goto nodata;
prefetchw(data + size);
@@ -196,6 +240,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
* the tail pointer in struct sk_buff!
*/
memset(skb, 0, offsetof(struct sk_buff, tail));
+ skb->pfmemalloc = pfmemalloc;
skb->truesize = size + sizeof(struct sk_buff);
atomic_set(&skb->users, 1);
skb->head = data;
@@ -212,7 +257,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
atomic_set(&shinfo->dataref, 1);
kmemcheck_annotate_variable(shinfo->destructor_arg);
- if (fclone) {
+ if (flags & SKB_ALLOC_FCLONE) {
struct sk_buff *child = skb + 1;
atomic_t *fclone_ref = (atomic_t *) (child + 1);
@@ -222,6 +267,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
atomic_set(fclone_ref, 1);
child->fclone = SKB_FCLONE_UNAVAILABLE;
+ child->pfmemalloc = pfmemalloc;
}
out:
return skb;
@@ -250,7 +296,8 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
{
struct sk_buff *skb;
- skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
+ skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask,
+ SKB_ALLOC_RX, NUMA_NO_NODE);
if (likely(skb)) {
skb_reserve(skb, NET_SKB_PAD);
skb->dev = dev;
@@ -527,6 +574,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
new->ipvs_property = old->ipvs_property;
#endif
+ new->pfmemalloc = old->pfmemalloc;
new->protocol = old->protocol;
new->mark = old->mark;
new->skb_iif = old->skb_iif;
@@ -621,6 +669,9 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
n->fclone = SKB_FCLONE_CLONE;
atomic_inc(fclone_ref);
} else {
+ if (skb_pfmemalloc(skb))
+ gfp_mask |= __GFP_MEMALLOC;
+
n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
if (!n)
return NULL;
@@ -657,6 +708,13 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
}
+static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
+{
+ if (skb_pfmemalloc((struct sk_buff *)skb))
+ return SKB_ALLOC_RX;
+ return 0;
+}
+
/**
* skb_copy - create private copy of an sk_buff
* @skb: buffer to copy
@@ -678,7 +736,8 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
{
int headerlen = skb_headroom(skb);
unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
- struct sk_buff *n = alloc_skb(size, gfp_mask);
+ struct sk_buff *n = __alloc_skb(size, gfp_mask,
+ skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
return NULL;
@@ -712,7 +771,8 @@ EXPORT_SYMBOL(skb_copy);
struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
{
unsigned int size = skb_end_pointer(skb) - skb->head;
- struct sk_buff *n = alloc_skb(size, gfp_mask);
+ struct sk_buff *n = __alloc_skb(size, gfp_mask,
+ skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
goto out;
@@ -803,7 +863,10 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
goto adjust_others;
}
- data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+ if (skb_pfmemalloc(skb))
+ gfp_mask |= __GFP_MEMALLOC;
+ data = kmalloc_reserve(size + sizeof(struct skb_shared_info), gfp_mask,
+ NUMA_NO_NODE, NULL);
if (!data)
goto nodata;
@@ -904,8 +967,9 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
/*
* Allocate the copy buffer
*/
- struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
- gfp_mask);
+ struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
+ gfp_mask, skb_alloc_rx_flag(skb),
+ NUMA_NO_NODE);
int oldheadroom = skb_headroom(skb);
int head_copy_len, head_copy_off;
int off;
@@ -2555,8 +2619,9 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
skb_release_head_state(nskb);
__skb_push(nskb, doffset);
} else {
- nskb = alloc_skb(hsize + doffset + headroom,
- GFP_ATOMIC);
+ nskb = __alloc_skb(hsize + doffset + headroom,
+ GFP_ATOMIC, skb_alloc_rx_flag(skb),
+ NUMA_NO_NODE);
if (unlikely(!nskb))
goto err;
diff --git a/net/core/sock.c b/net/core/sock.c
index 1deb48b..7aac82b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -219,6 +219,9 @@ __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
EXPORT_SYMBOL(sysctl_optmem_max);
+static DEFINE_MUTEX(memalloc_socks_lock);
+int memalloc_socks __read_mostly;
+
/**
* sk_set_memalloc - sets %SOCK_MEMALLOC
* @sk: socket to set it on
@@ -231,6 +234,9 @@ void sk_set_memalloc(struct sock *sk)
{
sock_set_flag(sk, SOCK_MEMALLOC);
sk->sk_allocation |= __GFP_MEMALLOC;
+ mutex_lock(&memalloc_socks_lock);
+ memalloc_socks++;
+ mutex_unlock(&memalloc_socks_lock);
}
EXPORT_SYMBOL_GPL(sk_set_memalloc);
@@ -238,6 +244,9 @@ void sk_clear_memalloc(struct sock *sk)
{
sock_reset_flag(sk, SOCK_MEMALLOC);
sk->sk_allocation &= ~__GFP_MEMALLOC;
+ mutex_lock(&memalloc_socks_lock);
+ memalloc_socks--;
+ mutex_unlock(&memalloc_socks_lock);
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Change the skb allocation API to indicate RX usage and use this to fall back
to the PFMEMALLOC reserve when needed. SKBs allocated from the reserve are
tagged in skb->pfmemalloc. If an SKB is allocated from the reserve and
the socket is later found to be unrelated to page reclaim, the packet is
dropped so that the memory remains available for page reclaim. Network
protocols are expected to recover from this packet loss.
[a.p.zijlstra@chello.nl: Ideas taken from various patches]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/gfp.h | 3 ++
include/linux/skbuff.h | 19 ++++++++--
include/net/sock.h | 6 +++
mm/internal.h | 3 --
net/core/filter.c | 8 ++++
net/core/skbuff.c | 95 ++++++++++++++++++++++++++++++++++++++++--------
net/core/sock.c | 9 +++++
7 files changed, 121 insertions(+), 22 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index d54eb02..ebf4d4f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -374,6 +374,9 @@ void drain_local_pages(void *dummy);
extern gfp_t gfp_allowed_mask;
+/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
+
extern void pm_restrict_gfp_mask(void);
extern void pm_restore_gfp_mask(void);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bf221d6..5cd4d23 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -393,6 +393,7 @@ struct sk_buff {
#else
__u8 deliver_no_wcard:1;
#endif
+ __u8 pfmemalloc:1;
__u8 ooo_okay:1;
kmemcheck_bitfield_end(flags2);
@@ -431,6 +432,15 @@ struct sk_buff {
#include <asm/system.h>
+#define SKB_ALLOC_FCLONE 0x01
+#define SKB_ALLOC_RX 0x02
+
+/* Returns true if the skb was allocated from PFMEMALLOC reserves */
+static inline bool skb_pfmemalloc(struct sk_buff *skb)
+{
+ return unlikely(skb->pfmemalloc);
+}
+
/*
* skb might have a dst pointer attached, refcounted or not.
* _skb_refdst low order bit is set if refcount was _not_ taken
@@ -488,7 +498,7 @@ extern void kfree_skb(struct sk_buff *skb);
extern void consume_skb(struct sk_buff *skb);
extern void __kfree_skb(struct sk_buff *skb);
extern struct sk_buff *__alloc_skb(unsigned int size,
- gfp_t priority, int fclone, int node);
+ gfp_t priority, int flags, int node);
static inline struct sk_buff *alloc_skb(unsigned int size,
gfp_t priority)
{
@@ -498,7 +508,7 @@ static inline struct sk_buff *alloc_skb(unsigned int size,
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
gfp_t priority)
{
- return __alloc_skb(size, priority, 1, NUMA_NO_NODE);
+ return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
}
extern bool skb_recycle_check(struct sk_buff *skb, int skb_size);
@@ -1524,7 +1534,8 @@ static inline void __skb_queue_purge(struct sk_buff_head *list)
static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
gfp_t gfp_mask)
{
- struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
+ struct sk_buff *skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask,
+ SKB_ALLOC_RX, NUMA_NO_NODE);
if (likely(skb))
skb_reserve(skb, NET_SKB_PAD);
return skb;
@@ -1575,7 +1586,7 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
*/
static inline struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask)
{
- return alloc_pages_node(NUMA_NO_NODE, gfp_mask, 0);
+ return alloc_pages_node(NUMA_NO_NODE, gfp_mask | __GFP_MEMALLOC, 0);
}
/**
diff --git a/include/net/sock.h b/include/net/sock.h
index e6ead99..1d8a26b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -585,6 +585,12 @@ static inline int sock_flag(struct sock *sk, enum sock_flags flag)
return test_bit(flag, &sk->sk_flags);
}
+extern int memalloc_socks;
+static inline int sk_memalloc_socks(void)
+{
+ return memalloc_socks;
+}
+
static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
{
return gfp_mask | (sk->sk_allocation & __GFP_MEMALLOC);
diff --git a/mm/internal.h b/mm/internal.h
index 110c9a2..6948820 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -189,9 +189,6 @@ static inline struct page *mem_map_next(struct page *iter,
#define __paginginit __init
#endif
-/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */
-bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);
-
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
diff --git a/net/core/filter.c b/net/core/filter.c
index afc5837..5223b48 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -138,6 +138,14 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
int err;
struct sk_filter *filter;
+ /*
+ * If the skb was allocated from pfmemalloc reserves, only
+ * allow SOCK_MEMALLOC sockets to use it as this socket is
+ * helping free memory
+ */
+ if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
+ return -ENOMEM;
+
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d883dcc..f3702ae 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -146,6 +146,43 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
BUG();
}
+
+/*
+ * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
+ * the caller if emergency pfmemalloc reserves are being used. If it is and
+ * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
+ * may be used. Otherwise, the packet data may be discarded until enough
+ * memory is free
+ */
+#define kmalloc_reserve(size, gfp, node, pfmemalloc) \
+ __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
+void *__kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip,
+ bool *pfmemalloc)
+{
+ void *obj;
+ bool ret_pfmemalloc = false;
+
+ /*
+ * Try a regular allocation, when that fails and we're not entitled
+ * to the reserves, fail.
+ */
+ obj = kmalloc_node_track_caller(size,
+ flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
+ node);
+ if (obj || !(gfp_pfmemalloc_allowed(flags)))
+ goto out;
+
+ /* Try again but now we are using pfmemalloc reserves */
+ ret_pfmemalloc = true;
+ obj = kmalloc_node_track_caller(size, flags, node);
+
+out:
+ if (pfmemalloc)
+ *pfmemalloc = ret_pfmemalloc;
+
+ return obj;
+}
+
/* Allocate a new skbuff. We do this ourselves so we can fill in a few
* 'private' fields and also do memory statistics to find all the
* [BEEP] leaks.
@@ -156,8 +193,10 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
* __alloc_skb - allocate a network buffer
* @size: size to allocate
* @gfp_mask: allocation mask
- * @fclone: allocate from fclone cache instead of head cache
- * and allocate a cloned (child) skb
+ * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
+ * instead of head cache and allocate a cloned (child) skb.
+ * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
+ * allocations in case the data is required for writeback
* @node: numa node to allocate memory on
*
* Allocate a new &sk_buff. The returned buffer has no headroom and a
@@ -168,14 +207,19 @@ static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
* %GFP_ATOMIC.
*/
struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
- int fclone, int node)
+ int flags, int node)
{
struct kmem_cache *cache;
struct skb_shared_info *shinfo;
struct sk_buff *skb;
u8 *data;
+ bool pfmemalloc;
+
+ cache = (flags & SKB_ALLOC_FCLONE)
+ ? skbuff_fclone_cache : skbuff_head_cache;
- cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
+ if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
+ gfp_mask |= __GFP_MEMALLOC;
/* Get the HEAD */
skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
@@ -184,8 +228,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
prefetchw(skb);
size = SKB_DATA_ALIGN(size);
- data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
- gfp_mask, node);
+ data = kmalloc_reserve(size + sizeof(struct skb_shared_info),
+ gfp_mask, node, &pfmemalloc);
if (!data)
goto nodata;
prefetchw(data + size);
@@ -196,6 +240,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
* the tail pointer in struct sk_buff!
*/
memset(skb, 0, offsetof(struct sk_buff, tail));
+ skb->pfmemalloc = pfmemalloc;
skb->truesize = size + sizeof(struct sk_buff);
atomic_set(&skb->users, 1);
skb->head = data;
@@ -212,7 +257,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
atomic_set(&shinfo->dataref, 1);
kmemcheck_annotate_variable(shinfo->destructor_arg);
- if (fclone) {
+ if (flags & SKB_ALLOC_FCLONE) {
struct sk_buff *child = skb + 1;
atomic_t *fclone_ref = (atomic_t *) (child + 1);
@@ -222,6 +267,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
atomic_set(fclone_ref, 1);
child->fclone = SKB_FCLONE_UNAVAILABLE;
+ child->pfmemalloc = pfmemalloc;
}
out:
return skb;
@@ -250,7 +296,8 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
{
struct sk_buff *skb;
- skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
+ skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask,
+ SKB_ALLOC_RX, NUMA_NO_NODE);
if (likely(skb)) {
skb_reserve(skb, NET_SKB_PAD);
skb->dev = dev;
@@ -527,6 +574,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
new->ipvs_property = old->ipvs_property;
#endif
+ new->pfmemalloc = old->pfmemalloc;
new->protocol = old->protocol;
new->mark = old->mark;
new->skb_iif = old->skb_iif;
@@ -621,6 +669,9 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
n->fclone = SKB_FCLONE_CLONE;
atomic_inc(fclone_ref);
} else {
+ if (skb_pfmemalloc(skb))
+ gfp_mask |= __GFP_MEMALLOC;
+
n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
if (!n)
return NULL;
@@ -657,6 +708,13 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
}
+static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
+{
+ if (skb_pfmemalloc((struct sk_buff *)skb))
+ return SKB_ALLOC_RX;
+ return 0;
+}
+
/**
* skb_copy - create private copy of an sk_buff
* @skb: buffer to copy
@@ -678,7 +736,8 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
{
int headerlen = skb_headroom(skb);
unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
- struct sk_buff *n = alloc_skb(size, gfp_mask);
+ struct sk_buff *n = __alloc_skb(size, gfp_mask,
+ skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
return NULL;
@@ -712,7 +771,8 @@ EXPORT_SYMBOL(skb_copy);
struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
{
unsigned int size = skb_end_pointer(skb) - skb->head;
- struct sk_buff *n = alloc_skb(size, gfp_mask);
+ struct sk_buff *n = __alloc_skb(size, gfp_mask,
+ skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
goto out;
@@ -803,7 +863,10 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
goto adjust_others;
}
- data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+ if (skb_pfmemalloc(skb))
+ gfp_mask |= __GFP_MEMALLOC;
+ data = kmalloc_reserve(size + sizeof(struct skb_shared_info), gfp_mask,
+ NUMA_NO_NODE, NULL);
if (!data)
goto nodata;
@@ -904,8 +967,9 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
/*
* Allocate the copy buffer
*/
- struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
- gfp_mask);
+ struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
+ gfp_mask, skb_alloc_rx_flag(skb),
+ NUMA_NO_NODE);
int oldheadroom = skb_headroom(skb);
int head_copy_len, head_copy_off;
int off;
@@ -2555,8 +2619,9 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
skb_release_head_state(nskb);
__skb_push(nskb, doffset);
} else {
- nskb = alloc_skb(hsize + doffset + headroom,
- GFP_ATOMIC);
+ nskb = __alloc_skb(hsize + doffset + headroom,
+ GFP_ATOMIC, skb_alloc_rx_flag(skb),
+ NUMA_NO_NODE);
if (unlikely(!nskb))
goto err;
diff --git a/net/core/sock.c b/net/core/sock.c
index 1deb48b..7aac82b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -219,6 +219,9 @@ __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
EXPORT_SYMBOL(sysctl_optmem_max);
+static DEFINE_MUTEX(memalloc_socks_lock);
+int memalloc_socks __read_mostly;
+
/**
* sk_set_memalloc - sets %SOCK_MEMALLOC
* @sk: socket to set it on
@@ -231,6 +234,9 @@ void sk_set_memalloc(struct sock *sk)
{
sock_set_flag(sk, SOCK_MEMALLOC);
sk->sk_allocation |= __GFP_MEMALLOC;
+ mutex_lock(&memalloc_socks_lock);
+ memalloc_socks++;
+ mutex_unlock(&memalloc_socks_lock);
}
EXPORT_SYMBOL_GPL(sk_set_memalloc);
@@ -238,6 +244,9 @@ void sk_clear_memalloc(struct sock *sk)
{
sock_reset_flag(sk, SOCK_MEMALLOC);
sk->sk_allocation &= ~__GFP_MEMALLOC;
+ mutex_lock(&memalloc_socks_lock);
+ memalloc_socks--;
+ mutex_unlock(&memalloc_socks_lock);
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 09/12] netvm: Set PF_MEMALLOC as appropriate during SKB processing
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
In order to make sure pfmemalloc packets receive all memory needed to proceed,
ensure processing of pfmemalloc SKBs happens under PF_MEMALLOC. This is
limited to a subset of protocols that are expected to be used for writing
to swap. Taps are not allowed to use PF_MEMALLOC as these are expected to
communicate with userspace processes which could be paged out.
[a.p.zijlstra@chello.nl: Ideas taken from various patches]
[jslaby@suse.cz: Lock imbalance fix]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 +++++
net/core/dev.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
net/core/sock.c | 16 ++++++++++++++++
3 files changed, 69 insertions(+), 4 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 1d8a26b..3ea9c2d 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -667,8 +667,13 @@ static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *s
return 0;
}
+extern int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+
static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
+ if (skb_pfmemalloc(skb))
+ return __sk_backlog_rcv(sk, skb);
+
return sk->sk_backlog_rcv(sk, skb);
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 6561021..6ab41f6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3012,6 +3012,27 @@ int __skb_bond_should_drop(struct sk_buff *skb, struct net_device *master)
}
EXPORT_SYMBOL(__skb_bond_should_drop);
+/*
+ * Limit which protocols can use the PFMEMALLOC reserves to those that are
+ * expected to be used for communication with swap.
+ */
+static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
+{
+ if (skb_pfmemalloc(skb))
+ switch (skb->protocol) {
+ case __constant_htons(ETH_P_ARP):
+ case __constant_htons(ETH_P_IP):
+ case __constant_htons(ETH_P_IPV6):
+ case __constant_htons(ETH_P_8021Q):
+ break;
+
+ default:
+ return false;
+ }
+
+ return true;
+}
+
static int __netif_receive_skb(struct sk_buff *skb)
{
struct packet_type *ptype, *pt_prev;
@@ -3022,15 +3043,28 @@ static int __netif_receive_skb(struct sk_buff *skb)
struct net_device *orig_or_bond;
int ret = NET_RX_DROP;
__be16 type;
+ unsigned long pflags = current->flags;
if (!netdev_tstamp_prequeue)
net_timestamp_check(skb);
trace_netif_receive_skb(skb);
+ /*
+ * PFMEMALLOC skbs are special, they should
+ * - be delivered to SOCK_MEMALLOC sockets only
+ * - stay away from userspace
+ * - have bounded memory usage
+ *
+ * Use PF_MEMALLOC as this saves us from propagating the allocation
+ * context down to all allocation sites.
+ */
+ if (skb_pfmemalloc(skb))
+ current->flags |= PF_MEMALLOC;
+
/* if we've gotten here through NAPI, check netpoll */
if (netpoll_receive_skb(skb))
- return NET_RX_DROP;
+ goto out;
if (!skb->skb_iif)
skb->skb_iif = skb->dev->ifindex;
@@ -3071,6 +3105,9 @@ static int __netif_receive_skb(struct sk_buff *skb)
}
#endif
+ if (skb_pfmemalloc(skb))
+ goto skip_taps;
+
list_for_each_entry_rcu(ptype, &ptype_all, list) {
if (ptype->dev == null_or_orig || ptype->dev == skb->dev ||
ptype->dev == orig_dev) {
@@ -3080,13 +3117,17 @@ static int __netif_receive_skb(struct sk_buff *skb)
}
}
+skip_taps:
#ifdef CONFIG_NET_CLS_ACT
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
ncls:
#endif
+ if (!skb_pfmemalloc_protocol(skb))
+ goto drop;
+
/* Handle special case of bridge or macvlan */
rx_handler = rcu_dereference(skb->dev->rx_handler);
if (rx_handler) {
@@ -3096,7 +3137,7 @@ ncls:
}
skb = rx_handler(skb);
if (!skb)
- goto out;
+ goto unlock;
}
if (vlan_tx_tag_present(skb)) {
@@ -3138,6 +3179,7 @@ ncls:
if (pt_prev) {
ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
} else {
+drop:
atomic_long_inc(&skb->dev->rx_dropped);
kfree_skb(skb);
/* Jamal, now you will not able to escape explaining
@@ -3146,8 +3188,10 @@ ncls:
ret = NET_RX_DROP;
}
-out:
+unlock:
rcu_read_unlock();
+out:
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return ret;
}
diff --git a/net/core/sock.c b/net/core/sock.c
index 7aac82b..eb38fbc 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -250,6 +250,22 @@ void sk_clear_memalloc(struct sock *sk)
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ int ret;
+ unsigned long pflags = current->flags;
+
+ /* these should have been dropped before queueing */
+ BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));
+
+ current->flags |= PF_MEMALLOC;
+ ret = sk->sk_backlog_rcv(sk, skb);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
+
+ return ret;
+}
+EXPORT_SYMBOL(__sk_backlog_rcv);
+
#if defined(CONFIG_CGROUPS) && !defined(CONFIG_NET_CLS_CGROUP)
int net_cls_subsys_id = -1;
EXPORT_SYMBOL_GPL(net_cls_subsys_id);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 09/12] netvm: Set PF_MEMALLOC as appropriate during SKB processing
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
In order to make sure pfmemalloc packets receive all memory needed to proceed,
ensure processing of pfmemalloc SKBs happens under PF_MEMALLOC. This is
limited to a subset of protocols that are expected to be used for writing
to swap. Taps are not allowed to use PF_MEMALLOC as these are expected to
communicate with userspace processes which could be paged out.
[a.p.zijlstra@chello.nl: Ideas taken from various patches]
[jslaby@suse.cz: Lock imbalance fix]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/net/sock.h | 5 +++++
net/core/dev.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
net/core/sock.c | 16 ++++++++++++++++
3 files changed, 69 insertions(+), 4 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 1d8a26b..3ea9c2d 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -667,8 +667,13 @@ static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *s
return 0;
}
+extern int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+
static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
+ if (skb_pfmemalloc(skb))
+ return __sk_backlog_rcv(sk, skb);
+
return sk->sk_backlog_rcv(sk, skb);
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 6561021..6ab41f6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3012,6 +3012,27 @@ int __skb_bond_should_drop(struct sk_buff *skb, struct net_device *master)
}
EXPORT_SYMBOL(__skb_bond_should_drop);
+/*
+ * Limit which protocols can use the PFMEMALLOC reserves to those that are
+ * expected to be used for communication with swap.
+ */
+static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
+{
+ if (skb_pfmemalloc(skb))
+ switch (skb->protocol) {
+ case __constant_htons(ETH_P_ARP):
+ case __constant_htons(ETH_P_IP):
+ case __constant_htons(ETH_P_IPV6):
+ case __constant_htons(ETH_P_8021Q):
+ break;
+
+ default:
+ return false;
+ }
+
+ return true;
+}
+
static int __netif_receive_skb(struct sk_buff *skb)
{
struct packet_type *ptype, *pt_prev;
@@ -3022,15 +3043,28 @@ static int __netif_receive_skb(struct sk_buff *skb)
struct net_device *orig_or_bond;
int ret = NET_RX_DROP;
__be16 type;
+ unsigned long pflags = current->flags;
if (!netdev_tstamp_prequeue)
net_timestamp_check(skb);
trace_netif_receive_skb(skb);
+ /*
+ * PFMEMALLOC skbs are special, they should
+ * - be delivered to SOCK_MEMALLOC sockets only
+ * - stay away from userspace
+ * - have bounded memory usage
+ *
+ * Use PF_MEMALLOC as this saves us from propagating the allocation
+ * context down to all allocation sites.
+ */
+ if (skb_pfmemalloc(skb))
+ current->flags |= PF_MEMALLOC;
+
/* if we've gotten here through NAPI, check netpoll */
if (netpoll_receive_skb(skb))
- return NET_RX_DROP;
+ goto out;
if (!skb->skb_iif)
skb->skb_iif = skb->dev->ifindex;
@@ -3071,6 +3105,9 @@ static int __netif_receive_skb(struct sk_buff *skb)
}
#endif
+ if (skb_pfmemalloc(skb))
+ goto skip_taps;
+
list_for_each_entry_rcu(ptype, &ptype_all, list) {
if (ptype->dev == null_or_orig || ptype->dev == skb->dev ||
ptype->dev == orig_dev) {
@@ -3080,13 +3117,17 @@ static int __netif_receive_skb(struct sk_buff *skb)
}
}
+skip_taps:
#ifdef CONFIG_NET_CLS_ACT
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
ncls:
#endif
+ if (!skb_pfmemalloc_protocol(skb))
+ goto drop;
+
/* Handle special case of bridge or macvlan */
rx_handler = rcu_dereference(skb->dev->rx_handler);
if (rx_handler) {
@@ -3096,7 +3137,7 @@ ncls:
}
skb = rx_handler(skb);
if (!skb)
- goto out;
+ goto unlock;
}
if (vlan_tx_tag_present(skb)) {
@@ -3138,6 +3179,7 @@ ncls:
if (pt_prev) {
ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
} else {
+drop:
atomic_long_inc(&skb->dev->rx_dropped);
kfree_skb(skb);
/* Jamal, now you will not able to escape explaining
@@ -3146,8 +3188,10 @@ ncls:
ret = NET_RX_DROP;
}
-out:
+unlock:
rcu_read_unlock();
+out:
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return ret;
}
diff --git a/net/core/sock.c b/net/core/sock.c
index 7aac82b..eb38fbc 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -250,6 +250,22 @@ void sk_clear_memalloc(struct sock *sk)
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ int ret;
+ unsigned long pflags = current->flags;
+
+ /* these should have been dropped before queueing */
+ BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));
+
+ current->flags |= PF_MEMALLOC;
+ ret = sk->sk_backlog_rcv(sk, skb);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
+
+ return ret;
+}
+EXPORT_SYMBOL(__sk_backlog_rcv);
+
#if defined(CONFIG_CGROUPS) && !defined(CONFIG_NET_CLS_CGROUP)
int net_cls_subsys_id = -1;
EXPORT_SYMBOL_GPL(net_cls_subsys_id);
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 10/12] mm: Micro-optimise slab to avoid a function call
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Getting and putting objects in SLAB currently requires a function call
but the bulk of the work is related to PFMEMALLOC reserves which are
only consumed when network-backed storage is critical. Use an inline
function to determine if the function call is required.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/slab.c | 28 ++++++++++++++++++++++++++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 8f81d17..0e9980b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -116,6 +116,8 @@
#include <linux/kmemcheck.h>
#include <linux/memory.h>
+#include <net/sock.h>
+
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -941,7 +943,7 @@ static void check_ac_pfmemalloc(struct kmem_cache *cachep,
ac->pfmemalloc = false;
}
-static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
gfp_t flags, bool force_refill)
{
int i;
@@ -988,7 +990,20 @@ static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
return objp;
}
-static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static inline void *ac_get_obj(struct kmem_cache *cachep,
+ struct array_cache *ac, gfp_t flags, bool force_refill)
+{
+ void *objp;
+
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_get_obj(cachep, ac, flags, force_refill);
+ else
+ objp = ac->entry[--ac->avail];
+
+ return objp;
+}
+
+static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
void *objp)
{
struct slab *slabp;
@@ -1001,6 +1016,15 @@ static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
set_obj_pfmemalloc(&objp);
}
+ return objp;
+}
+
+static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ void *objp)
+{
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_put_obj(cachep, ac, objp);
+
ac->entry[ac->avail++] = objp;
}
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 10/12] mm: Micro-optimise slab to avoid a function call
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Getting and putting objects in SLAB currently requires a function call
but the bulk of the work is related to PFMEMALLOC reserves which are
only consumed when network-backed storage is critical. Use an inline
function to determine if the function call is required.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/slab.c | 28 ++++++++++++++++++++++++++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 8f81d17..0e9980b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -116,6 +116,8 @@
#include <linux/kmemcheck.h>
#include <linux/memory.h>
+#include <net/sock.h>
+
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -941,7 +943,7 @@ static void check_ac_pfmemalloc(struct kmem_cache *cachep,
ac->pfmemalloc = false;
}
-static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
gfp_t flags, bool force_refill)
{
int i;
@@ -988,7 +990,20 @@ static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
return objp;
}
-static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static inline void *ac_get_obj(struct kmem_cache *cachep,
+ struct array_cache *ac, gfp_t flags, bool force_refill)
+{
+ void *objp;
+
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_get_obj(cachep, ac, flags, force_refill);
+ else
+ objp = ac->entry[--ac->avail];
+
+ return objp;
+}
+
+static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
void *objp)
{
struct slab *slabp;
@@ -1001,6 +1016,15 @@ static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
set_obj_pfmemalloc(&objp);
}
+ return objp;
+}
+
+static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ void *objp)
+{
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_put_obj(cachep, ac, objp);
+
ac->entry[ac->avail++] = objp;
}
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 11/12] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Set SOCK_MEMALLOC on the NBD socket to allow access to PFMEMALLOC
reserves so pages backed by NBD, particularly if swap related,
can be cleaned to prevent the machine being deadlocked. It is
still possible that the PFMEMALLOC reserves get depleted resulting
in deadlock but this can be resolved by the administrator by
increasing min_free_kbytes.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
drivers/block/nbd.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index e6fc716..322cef8 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -156,6 +156,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
struct msghdr msg;
struct kvec iov;
sigset_t blocked, oldset;
+ unsigned long pflags = current->flags;
if (unlikely(!sock)) {
printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
@@ -168,8 +169,9 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
siginitsetinv(&blocked, sigmask(SIGKILL));
sigprocmask(SIG_SETMASK, &blocked, &oldset);
+ current->flags |= PF_MEMALLOC;
do {
- sock->sk->sk_allocation = GFP_NOIO;
+ sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
iov.iov_base = buf;
iov.iov_len = size;
msg.msg_name = NULL;
@@ -214,6 +216,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
} while (size > 0);
sigprocmask(SIG_SETMASK, &oldset, NULL);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return result;
}
@@ -404,6 +407,8 @@ static int nbd_do_it(struct nbd_device *lo)
BUG_ON(lo->magic != LO_MAGIC);
+ sk_set_memalloc(lo->sock->sk);
+
lo->pid = current->pid;
ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
if (ret) {
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 11/12] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
Set SOCK_MEMALLOC on the NBD socket to allow access to PFMEMALLOC
reserves so pages backed by NBD, particularly if swap related,
can be cleaned to prevent the machine being deadlocked. It is
still possible that the PFMEMALLOC reserves get depleted resulting
in deadlock but this can be resolved by the administrator by
increasing min_free_kbytes.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
drivers/block/nbd.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index e6fc716..322cef8 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -156,6 +156,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
struct msghdr msg;
struct kvec iov;
sigset_t blocked, oldset;
+ unsigned long pflags = current->flags;
if (unlikely(!sock)) {
printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
@@ -168,8 +169,9 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
siginitsetinv(&blocked, sigmask(SIGKILL));
sigprocmask(SIG_SETMASK, &blocked, &oldset);
+ current->flags |= PF_MEMALLOC;
do {
- sock->sk->sk_allocation = GFP_NOIO;
+ sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
iov.iov_base = buf;
iov.iov_len = size;
msg.msg_name = NULL;
@@ -214,6 +216,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
} while (size > 0);
sigprocmask(SIG_SETMASK, &oldset, NULL);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return result;
}
@@ -404,6 +407,8 @@ static int nbd_do_it(struct nbd_device *lo)
BUG_ON(lo->magic != LO_MAGIC);
+ sk_set_memalloc(lo->sock->sk);
+
lo->pid = current->pid;
ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
if (ret) {
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 10:41 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
If swap is backed by network storage such as NBD, there is a risk that a
large number of reclaimers can hang the system by consuming all
PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
min_free_kbytes in advance. This patch will throttle direct reclaimers
if half the PF_MEMALLOC reserves are in use as the system is at risk of
hanging. A message will be displayed so the administrator knows that
min_free_kbytes should be tuned to a higher value to avoid the
throttling in the future.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/mmzone.h | 1 +
mm/page_alloc.c | 1 +
mm/vmscan.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 02ecb01..e86dcaf 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -638,6 +638,7 @@ typedef struct pglist_data {
range, including holes */
int node_id;
wait_queue_head_t kswapd_wait;
+ wait_queue_head_t pfmemalloc_wait;
struct task_struct *kswapd;
int kswapd_max_order;
enum zone_type classzone_idx;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2b87dfd..4b1170f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4160,6 +4160,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
pgdat_resize_init(pgdat);
pgdat->nr_zones = 0;
init_waitqueue_head(&pgdat->kswapd_wait);
+ init_waitqueue_head(&pgdat->pfmemalloc_wait);
pgdat->kswapd_max_order = 0;
pgdat_page_cgroup_init(pgdat);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6771ea7..2dad23d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -42,6 +42,8 @@
#include <linux/delayacct.h>
#include <linux/sysctl.h>
+#include <net/sock.h>
+
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -2115,6 +2117,61 @@ out:
return 0;
}
+static bool pfmemalloc_watermark_ok(pg_data_t *pgdat, int high_zoneidx)
+{
+ struct zone *zone;
+ unsigned long pfmemalloc_reserve = 0;
+ unsigned long free_pages = 0;
+ int i;
+
+ for (i = 0; i <= high_zoneidx; i++) {
+ zone = &pgdat->node_zones[i];
+ pfmemalloc_reserve += min_wmark_pages(zone);
+ free_pages += zone_page_state(zone, NR_FREE_PAGES);
+ }
+
+ return (free_pages > pfmemalloc_reserve / 2) ? true : false;
+}
+
+/*
+ * Throttle direct reclaimers if backing storage is backed by the network
+ * and the PFMEMALLOC reserve for the preferred node is getting dangerously
+ * depleted. kswapd will continue to make progress and wake the processes
+ * when the low watermark is reached
+ */
+static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
+ nodemask_t *nodemask)
+{
+ struct zone *zone;
+ int high_zoneidx = gfp_zone(gfp_mask);
+ DEFINE_WAIT(wait);
+
+ /*
+ * Only worry about the PFMEMALLOC reserves when network-backed
+ * storage is configured.
+ */
+ if (!sk_memalloc_socks())
+ return;
+
+ /* Check if the pfmemalloc reserves are ok */
+ first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
+ if (pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx))
+ return;
+
+ /* Throttle */
+ if (printk_ratelimit())
+ printk(KERN_INFO "Throttling %s due to reclaim pressure on "
+ "network storage\n",
+ current->comm);
+ do {
+ prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
+ TASK_INTERRUPTIBLE);
+ schedule();
+ finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
+ } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
+ !fatal_signal_pending(current));
+}
+
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
gfp_t gfp_mask, nodemask_t *nodemask)
{
@@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
.nodemask = nodemask,
};
+ throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
+
trace_mm_vmscan_direct_reclaim_begin(order,
sc.may_writepage,
gfp_mask);
@@ -2482,6 +2541,13 @@ loop_again:
}
}
+
+ /* Wake throttled direct reclaimers if low watermark is met */
+ if (sk_memalloc_socks() &&
+ waitqueue_active(&pgdat->pfmemalloc_wait) &&
+ pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
+ wake_up_interruptible(&pgdat->pfmemalloc_wait);
+
if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
break; /* kswapd: all done */
/*
--
1.7.3.4
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
@ 2011-04-14 10:41 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-14 10:41 UTC (permalink / raw)
To: Linux-MM, Linux-Netdev; +Cc: LKML, Peter Zijlstra, Mel Gorman
If swap is backed by network storage such as NBD, there is a risk that a
large number of reclaimers can hang the system by consuming all
PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
min_free_kbytes in advance. This patch will throttle direct reclaimers
if half the PF_MEMALLOC reserves are in use as the system is at risk of
hanging. A message will be displayed so the administrator knows that
min_free_kbytes should be tuned to a higher value to avoid the
throttling in the future.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/mmzone.h | 1 +
mm/page_alloc.c | 1 +
mm/vmscan.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 02ecb01..e86dcaf 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -638,6 +638,7 @@ typedef struct pglist_data {
range, including holes */
int node_id;
wait_queue_head_t kswapd_wait;
+ wait_queue_head_t pfmemalloc_wait;
struct task_struct *kswapd;
int kswapd_max_order;
enum zone_type classzone_idx;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2b87dfd..4b1170f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4160,6 +4160,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
pgdat_resize_init(pgdat);
pgdat->nr_zones = 0;
init_waitqueue_head(&pgdat->kswapd_wait);
+ init_waitqueue_head(&pgdat->pfmemalloc_wait);
pgdat->kswapd_max_order = 0;
pgdat_page_cgroup_init(pgdat);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6771ea7..2dad23d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -42,6 +42,8 @@
#include <linux/delayacct.h>
#include <linux/sysctl.h>
+#include <net/sock.h>
+
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -2115,6 +2117,61 @@ out:
return 0;
}
+static bool pfmemalloc_watermark_ok(pg_data_t *pgdat, int high_zoneidx)
+{
+ struct zone *zone;
+ unsigned long pfmemalloc_reserve = 0;
+ unsigned long free_pages = 0;
+ int i;
+
+ for (i = 0; i <= high_zoneidx; i++) {
+ zone = &pgdat->node_zones[i];
+ pfmemalloc_reserve += min_wmark_pages(zone);
+ free_pages += zone_page_state(zone, NR_FREE_PAGES);
+ }
+
+ return (free_pages > pfmemalloc_reserve / 2) ? true : false;
+}
+
+/*
+ * Throttle direct reclaimers if backing storage is backed by the network
+ * and the PFMEMALLOC reserve for the preferred node is getting dangerously
+ * depleted. kswapd will continue to make progress and wake the processes
+ * when the low watermark is reached
+ */
+static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
+ nodemask_t *nodemask)
+{
+ struct zone *zone;
+ int high_zoneidx = gfp_zone(gfp_mask);
+ DEFINE_WAIT(wait);
+
+ /*
+ * Only worry about the PFMEMALLOC reserves when network-backed
+ * storage is configured.
+ */
+ if (!sk_memalloc_socks())
+ return;
+
+ /* Check if the pfmemalloc reserves are ok */
+ first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
+ if (pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx))
+ return;
+
+ /* Throttle */
+ if (printk_ratelimit())
+ printk(KERN_INFO "Throttling %s due to reclaim pressure on "
+ "network storage\n",
+ current->comm);
+ do {
+ prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
+ TASK_INTERRUPTIBLE);
+ schedule();
+ finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
+ } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
+ !fatal_signal_pending(current));
+}
+
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
gfp_t gfp_mask, nodemask_t *nodemask)
{
@@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
.nodemask = nodemask,
};
+ throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
+
trace_mm_vmscan_direct_reclaim_begin(order,
sc.may_writepage,
gfp_mask);
@@ -2482,6 +2541,13 @@ loop_again:
}
}
+
+ /* Wake throttled direct reclaimers if low watermark is met */
+ if (sk_memalloc_socks() &&
+ waitqueue_active(&pgdat->pfmemalloc_wait) &&
+ pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
+ wake_up_interruptible(&pgdat->pfmemalloc_wait);
+
if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
break; /* kswapd: all done */
/*
--
1.7.3.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 38+ messages in thread
* Re: [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-14 21:33 ` David Miller
-1 siblings, 0 replies; 38+ messages in thread
From: David Miller @ 2011-04-14 21:33 UTC (permalink / raw)
To: mgorman; +Cc: linux-mm, netdev, linux-kernel, a.p.zijlstra
From: Mel Gorman <mgorman@suse.de>
Date: Thu, 14 Apr 2011 11:41:34 +0100
> +extern int memalloc_socks;
> +static inline int sk_memalloc_socks(void)
> +{
> + return memalloc_socks;
> +}
> +
...
> +static DEFINE_MUTEX(memalloc_socks_lock);
> +int memalloc_socks __read_mostly;
Please use an atomic_t, it has to be more efficient than this mutex
business.
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
@ 2011-04-14 21:33 ` David Miller
0 siblings, 0 replies; 38+ messages in thread
From: David Miller @ 2011-04-14 21:33 UTC (permalink / raw)
To: mgorman; +Cc: linux-mm, netdev, linux-kernel, a.p.zijlstra
From: Mel Gorman <mgorman@suse.de>
Date: Thu, 14 Apr 2011 11:41:34 +0100
> +extern int memalloc_socks;
> +static inline int sk_memalloc_socks(void)
> +{
> + return memalloc_socks;
> +}
> +
...
> +static DEFINE_MUTEX(memalloc_socks_lock);
> +int memalloc_socks __read_mostly;
Please use an atomic_t, it has to be more efficient than this mutex
business.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
2011-04-14 21:33 ` David Miller
@ 2011-04-15 10:44 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-15 10:44 UTC (permalink / raw)
To: David Miller; +Cc: linux-mm, netdev, linux-kernel, a.p.zijlstra
On Thu, Apr 14, 2011 at 02:33:35PM -0700, David Miller wrote:
> From: Mel Gorman <mgorman@suse.de>
> Date: Thu, 14 Apr 2011 11:41:34 +0100
>
> > +extern int memalloc_socks;
> > +static inline int sk_memalloc_socks(void)
> > +{
> > + return memalloc_socks;
> > +}
> > +
> ...
> > +static DEFINE_MUTEX(memalloc_socks_lock);
> > +int memalloc_socks __read_mostly;
>
> Please use an atomic_t, it has to be more efficient than this mutex
> business.
Will fix.
Thanks.
--
Mel Gorman
SUSE Labs
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves
@ 2011-04-15 10:44 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-15 10:44 UTC (permalink / raw)
To: David Miller; +Cc: linux-mm, netdev, linux-kernel, a.p.zijlstra
On Thu, Apr 14, 2011 at 02:33:35PM -0700, David Miller wrote:
> From: Mel Gorman <mgorman@suse.de>
> Date: Thu, 14 Apr 2011 11:41:34 +0100
>
> > +extern int memalloc_socks;
> > +static inline int sk_memalloc_socks(void)
> > +{
> > + return memalloc_socks;
> > +}
> > +
> ...
> > +static DEFINE_MUTEX(memalloc_socks_lock);
> > +int memalloc_socks __read_mostly;
>
> Please use an atomic_t, it has to be more efficient than this mutex
> business.
Will fix.
Thanks.
--
Mel Gorman
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-18 12:30 ` NeilBrown
-1 siblings, 0 replies; 38+ messages in thread
From: NeilBrown @ 2011-04-18 12:30 UTC (permalink / raw)
To: Mel Gorman; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
> If swap is backed by network storage such as NBD, there is a risk that a
> large number of reclaimers can hang the system by consuming all
> PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> min_free_kbytes in advance. This patch will throttle direct reclaimers
> if half the PF_MEMALLOC reserves are in use as the system is at risk of
> hanging. A message will be displayed so the administrator knows that
> min_free_kbytes should be tuned to a higher value to avoid the
> throttling in the future.
This sounds like a much simpler approach than all the pre-allocation.
Is it certain to work? Are PF_MEMALLOC reserved only used from direct
reclaim?
Is printing a message for the admin really a good idea? Auto-tuning is much
better than requiring the sysadmin to tune.
Is throttling when we are low on memory really a problem that needs to be
tuned away? Presumably we would get over the memory shortage fairly soon and
the throttling would stop (??).
> + if (printk_ratelimit())
> + printk(KERN_INFO "Throttling %s due to reclaim pressure on "
> + "network storage\n",
> + current->comm);
> + do {
> + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> + TASK_INTERRUPTIBLE);
> + schedule();
> + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
> + !fatal_signal_pending(current));
> +}
> +
This looks racing. It is my understanding that you should always perform the
test between the 'prepare_to_wait' and the 'schedule'. Otherwise the wakeup
could happen just before the prepare_to_wait and you never wake from the
schedule.
If that doesn't apply in this case I would appreciate a comment explaining
why.
> unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> gfp_t gfp_mask, nodemask_t *nodemask)
> {
> @@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> .nodemask = nodemask,
> };
>
> + throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
> +
> trace_mm_vmscan_direct_reclaim_begin(order,
> sc.may_writepage,
> gfp_mask);
> @@ -2482,6 +2541,13 @@ loop_again:
> }
>
> }
> +
> + /* Wake throttled direct reclaimers if low watermark is met */
> + if (sk_memalloc_socks() &&
> + waitqueue_active(&pgdat->pfmemalloc_wait) &&
> + pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
> + wake_up_interruptible(&pgdat->pfmemalloc_wait);
> +
This test on sk_memalloc_socks looks ugly to me.
The VM shouldn't be checking on some networking state.
Do we really need the test? It is not reasonable to always throttle direct
reclaim when mem gets really low?
If we do need the test - could networking set some global flag in the VM
which the VM can then test.
Maybe one day we will have something other than network which needs special
care with the last dregs of memory - then it could set the global flag too
(in which case it should probably be a global counter).
Thanks,
NeilBrown
> if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
> break; /* kswapd: all done */
> /*
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
@ 2011-04-18 12:30 ` NeilBrown
0 siblings, 0 replies; 38+ messages in thread
From: NeilBrown @ 2011-04-18 12:30 UTC (permalink / raw)
To: Mel Gorman; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
> If swap is backed by network storage such as NBD, there is a risk that a
> large number of reclaimers can hang the system by consuming all
> PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> min_free_kbytes in advance. This patch will throttle direct reclaimers
> if half the PF_MEMALLOC reserves are in use as the system is at risk of
> hanging. A message will be displayed so the administrator knows that
> min_free_kbytes should be tuned to a higher value to avoid the
> throttling in the future.
This sounds like a much simpler approach than all the pre-allocation.
Is it certain to work? Are PF_MEMALLOC reserved only used from direct
reclaim?
Is printing a message for the admin really a good idea? Auto-tuning is much
better than requiring the sysadmin to tune.
Is throttling when we are low on memory really a problem that needs to be
tuned away? Presumably we would get over the memory shortage fairly soon and
the throttling would stop (??).
> + if (printk_ratelimit())
> + printk(KERN_INFO "Throttling %s due to reclaim pressure on "
> + "network storage\n",
> + current->comm);
> + do {
> + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> + TASK_INTERRUPTIBLE);
> + schedule();
> + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
> + !fatal_signal_pending(current));
> +}
> +
This looks racing. It is my understanding that you should always perform the
test between the 'prepare_to_wait' and the 'schedule'. Otherwise the wakeup
could happen just before the prepare_to_wait and you never wake from the
schedule.
If that doesn't apply in this case I would appreciate a comment explaining
why.
> unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> gfp_t gfp_mask, nodemask_t *nodemask)
> {
> @@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> .nodemask = nodemask,
> };
>
> + throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
> +
> trace_mm_vmscan_direct_reclaim_begin(order,
> sc.may_writepage,
> gfp_mask);
> @@ -2482,6 +2541,13 @@ loop_again:
> }
>
> }
> +
> + /* Wake throttled direct reclaimers if low watermark is met */
> + if (sk_memalloc_socks() &&
> + waitqueue_active(&pgdat->pfmemalloc_wait) &&
> + pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
> + wake_up_interruptible(&pgdat->pfmemalloc_wait);
> +
This test on sk_memalloc_socks looks ugly to me.
The VM shouldn't be checking on some networking state.
Do we really need the test? It is not reasonable to always throttle direct
reclaim when mem gets really low?
If we do need the test - could networking set some global flag in the VM
which the VM can then test.
Maybe one day we will have something other than network which needs special
care with the last dregs of memory - then it could set the global flag too
(in which case it should probably be a global counter).
Thanks,
NeilBrown
> if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
> break; /* kswapd: all done */
> /*
--
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^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
2011-04-14 10:41 ` Mel Gorman
@ 2011-04-18 12:32 ` NeilBrown
-1 siblings, 0 replies; 38+ messages in thread
From: NeilBrown @ 2011-04-18 12:32 UTC (permalink / raw)
To: Mel Gorman; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
> If swap is backed by network storage such as NBD, there is a risk that a
> large number of reclaimers can hang the system by consuming all
> PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> min_free_kbytes in advance. This patch will throttle direct reclaimers
> if half the PF_MEMALLOC reserves are in use as the system is at risk of
> hanging. A message will be displayed so the administrator knows that
> min_free_kbytes should be tuned to a higher value to avoid the
> throttling in the future.
>
(I knew there was something else).
I understand that there are suggestions that direct reclaim should always be
serialised as this reduces lock contention and improve data patterns (or
something like that).
Would that make this patch redundant? Or does this provide some extra
guarantee that the other proposal would not?
Thanks again,
NeilBrown
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
@ 2011-04-18 12:32 ` NeilBrown
0 siblings, 0 replies; 38+ messages in thread
From: NeilBrown @ 2011-04-18 12:32 UTC (permalink / raw)
To: Mel Gorman; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
> If swap is backed by network storage such as NBD, there is a risk that a
> large number of reclaimers can hang the system by consuming all
> PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> min_free_kbytes in advance. This patch will throttle direct reclaimers
> if half the PF_MEMALLOC reserves are in use as the system is at risk of
> hanging. A message will be displayed so the administrator knows that
> min_free_kbytes should be tuned to a higher value to avoid the
> throttling in the future.
>
(I knew there was something else).
I understand that there are suggestions that direct reclaim should always be
serialised as this reduces lock contention and improve data patterns (or
something like that).
Would that make this patch redundant? Or does this provide some extra
guarantee that the other proposal would not?
Thanks again,
NeilBrown
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
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^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
2011-04-18 12:30 ` NeilBrown
@ 2011-04-18 14:04 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-18 14:04 UTC (permalink / raw)
To: NeilBrown; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Mon, Apr 18, 2011 at 10:30:14PM +1000, NeilBrown wrote:
> On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
>
> > If swap is backed by network storage such as NBD, there is a risk that a
> > large number of reclaimers can hang the system by consuming all
> > PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> > min_free_kbytes in advance. This patch will throttle direct reclaimers
> > if half the PF_MEMALLOC reserves are in use as the system is at risk of
> > hanging. A message will be displayed so the administrator knows that
> > min_free_kbytes should be tuned to a higher value to avoid the
> > throttling in the future.
>
> This sounds like a much simpler approach than all the pre-allocation.
> Is it certain to work?
It should - at least I haven't conceived of a situation where it would
fail yet nor have I triggered the throttling logic during tests. The
logic was tested with a debugging patch that set the throttling
level higher.
> Are PF_MEMALLOC reserved only used from direct
> reclaim?
>
No. They are also used by kswapd and by a task that is being OOM killed.
> Is printing a message for the admin really a good idea?
Ordinarily no but initially I wanted to make it brutually obvious
when throttling is hit and what got hit. Ultimately it's more likely
to be a tracepoint.
> Auto-tuning is much
> better than requiring the sysadmin to tune.
That requires the memory reservation and pre-allocation patches. To
keep complexity down, I wanted to treat that as a separate series.
> Is throttling when we are low on memory really a problem that needs to be
> tuned away? Presumably we would get over the memory shortage fairly soon and
> the throttling would stop (??).
>
It depends on what the administrator wants really. If they don't care
about the stall, they can simply ignore the problem because as you say,
it should get resolved quickly and the throttled processes continue.
> > + if (printk_ratelimit())
> > + printk(KERN_INFO "Throttling %s due to reclaim pressure on "
> > + "network storage\n",
> > + current->comm);
> > + do {
> > + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> > + TASK_INTERRUPTIBLE);
> > + schedule();
> > + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> > + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
> > + !fatal_signal_pending(current));
> > +}
> > +
>
> This looks racing. It is my understanding that you should always perform the
> test between the 'prepare_to_wait' and the 'schedule'. Otherwise the wakeup
> could happen just before the prepare_to_wait and you never wake from the
> schedule.
> If that doesn't apply in this case I would appreciate a comment explaining
> why.
>
You're right, it's racy. Well spotted.
>
>
> > unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > gfp_t gfp_mask, nodemask_t *nodemask)
> > {
> > @@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > .nodemask = nodemask,
> > };
> >
> > + throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
> > +
> > trace_mm_vmscan_direct_reclaim_begin(order,
> > sc.may_writepage,
> > gfp_mask);
> > @@ -2482,6 +2541,13 @@ loop_again:
> > }
> >
> > }
> > +
> > + /* Wake throttled direct reclaimers if low watermark is met */
> > + if (sk_memalloc_socks() &&
> > + waitqueue_active(&pgdat->pfmemalloc_wait) &&
> > + pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
> > + wake_up_interruptible(&pgdat->pfmemalloc_wait);
> > +
>
> This test on sk_memalloc_socks looks ugly to me.
> The VM shouldn't be checking on some networking state.
> Do we really need the test? It is not reasonable to always throttle direct
> reclaim when mem gets really low?
It's a micro-optimisation. Throttling is not currently necessary
as backing storage such as local block devices have mempools in
place that avoid dipping into the PF_MEMALLOC reserves. On a normal
configuration, that waitqueue will simply never be active so I can
remove the sk_memalloc_socks() test.
What about in slab though? A function call in the fast path is avoided
by using the sk_memalloc_socks tests which is nice.
> If we do need the test - could networking set some global flag in the VM
> which the VM can then test.
I'd like to keep the test in slab at least but adding a new global flag
feels like a waste. I could add a VM wrapper around sk_memalloc_socks()
that would effectively be a rename but that doesn't seem much better.
> Maybe one day we will have something other than network which needs special
> care with the last dregs of memory - then it could set the global flag too
> (in which case it should probably be a global counter).
>
When/if that happens, the naming would become more obvious. Right now,
it's network-related so doesn't seem unreasonable to have a
network-related check.
--
Mel Gorman
SUSE Labs
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
@ 2011-04-18 14:04 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-18 14:04 UTC (permalink / raw)
To: NeilBrown; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Mon, Apr 18, 2011 at 10:30:14PM +1000, NeilBrown wrote:
> On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
>
> > If swap is backed by network storage such as NBD, there is a risk that a
> > large number of reclaimers can hang the system by consuming all
> > PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> > min_free_kbytes in advance. This patch will throttle direct reclaimers
> > if half the PF_MEMALLOC reserves are in use as the system is at risk of
> > hanging. A message will be displayed so the administrator knows that
> > min_free_kbytes should be tuned to a higher value to avoid the
> > throttling in the future.
>
> This sounds like a much simpler approach than all the pre-allocation.
> Is it certain to work?
It should - at least I haven't conceived of a situation where it would
fail yet nor have I triggered the throttling logic during tests. The
logic was tested with a debugging patch that set the throttling
level higher.
> Are PF_MEMALLOC reserved only used from direct
> reclaim?
>
No. They are also used by kswapd and by a task that is being OOM killed.
> Is printing a message for the admin really a good idea?
Ordinarily no but initially I wanted to make it brutually obvious
when throttling is hit and what got hit. Ultimately it's more likely
to be a tracepoint.
> Auto-tuning is much
> better than requiring the sysadmin to tune.
That requires the memory reservation and pre-allocation patches. To
keep complexity down, I wanted to treat that as a separate series.
> Is throttling when we are low on memory really a problem that needs to be
> tuned away? Presumably we would get over the memory shortage fairly soon and
> the throttling would stop (??).
>
It depends on what the administrator wants really. If they don't care
about the stall, they can simply ignore the problem because as you say,
it should get resolved quickly and the throttled processes continue.
> > + if (printk_ratelimit())
> > + printk(KERN_INFO "Throttling %s due to reclaim pressure on "
> > + "network storage\n",
> > + current->comm);
> > + do {
> > + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> > + TASK_INTERRUPTIBLE);
> > + schedule();
> > + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> > + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
> > + !fatal_signal_pending(current));
> > +}
> > +
>
> This looks racing. It is my understanding that you should always perform the
> test between the 'prepare_to_wait' and the 'schedule'. Otherwise the wakeup
> could happen just before the prepare_to_wait and you never wake from the
> schedule.
> If that doesn't apply in this case I would appreciate a comment explaining
> why.
>
You're right, it's racy. Well spotted.
>
>
> > unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > gfp_t gfp_mask, nodemask_t *nodemask)
> > {
> > @@ -2131,6 +2188,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > .nodemask = nodemask,
> > };
> >
> > + throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
> > +
> > trace_mm_vmscan_direct_reclaim_begin(order,
> > sc.may_writepage,
> > gfp_mask);
> > @@ -2482,6 +2541,13 @@ loop_again:
> > }
> >
> > }
> > +
> > + /* Wake throttled direct reclaimers if low watermark is met */
> > + if (sk_memalloc_socks() &&
> > + waitqueue_active(&pgdat->pfmemalloc_wait) &&
> > + pfmemalloc_watermark_ok(pgdat, MAX_NR_ZONES - 1))
> > + wake_up_interruptible(&pgdat->pfmemalloc_wait);
> > +
>
> This test on sk_memalloc_socks looks ugly to me.
> The VM shouldn't be checking on some networking state.
> Do we really need the test? It is not reasonable to always throttle direct
> reclaim when mem gets really low?
It's a micro-optimisation. Throttling is not currently necessary
as backing storage such as local block devices have mempools in
place that avoid dipping into the PF_MEMALLOC reserves. On a normal
configuration, that waitqueue will simply never be active so I can
remove the sk_memalloc_socks() test.
What about in slab though? A function call in the fast path is avoided
by using the sk_memalloc_socks tests which is nice.
> If we do need the test - could networking set some global flag in the VM
> which the VM can then test.
I'd like to keep the test in slab at least but adding a new global flag
feels like a waste. I could add a VM wrapper around sk_memalloc_socks()
that would effectively be a rename but that doesn't seem much better.
> Maybe one day we will have something other than network which needs special
> care with the last dregs of memory - then it could set the global flag too
> (in which case it should probably be a global counter).
>
When/if that happens, the naming would become more obvious. Right now,
it's network-related so doesn't seem unreasonable to have a
network-related check.
--
Mel Gorman
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
2011-04-18 12:32 ` NeilBrown
@ 2011-04-18 14:08 ` Mel Gorman
-1 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-18 14:08 UTC (permalink / raw)
To: NeilBrown; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Mon, Apr 18, 2011 at 10:32:51PM +1000, NeilBrown wrote:
> On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
>
> > If swap is backed by network storage such as NBD, there is a risk that a
> > large number of reclaimers can hang the system by consuming all
> > PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> > min_free_kbytes in advance. This patch will throttle direct reclaimers
> > if half the PF_MEMALLOC reserves are in use as the system is at risk of
> > hanging. A message will be displayed so the administrator knows that
> > min_free_kbytes should be tuned to a higher value to avoid the
> > throttling in the future.
> >
>
> (I knew there was something else).
>
> I understand that there are suggestions that direct reclaim should always be
> serialised as this reduces lock contention and improve data patterns (or
> something like that).
>
AFAIK, this suggestion never got much beyond the "hand-waving" stage
of development. It tended to trip up on the fact that such a feature
could also throttle processes on machines with plenty of free clean
unmapped pagecache which would be undesirable.
> Would that make this patch redundant?
Depends on how it was being serialised but ....
> Or does this provide some extra
> guarantee that the other proposal would not?
>
This patch could be extended to serialise direct reclaims in situations
other than PFMEMALLOC is low if someone demonstrated the benefit.
--
Mel Gorman
SUSE Labs
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
@ 2011-04-18 14:08 ` Mel Gorman
0 siblings, 0 replies; 38+ messages in thread
From: Mel Gorman @ 2011-04-18 14:08 UTC (permalink / raw)
To: NeilBrown; +Cc: Linux-MM, Linux-Netdev, LKML, Peter Zijlstra
On Mon, Apr 18, 2011 at 10:32:51PM +1000, NeilBrown wrote:
> On Thu, 14 Apr 2011 11:41:38 +0100 Mel Gorman <mgorman@suse.de> wrote:
>
> > If swap is backed by network storage such as NBD, there is a risk that a
> > large number of reclaimers can hang the system by consuming all
> > PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
> > min_free_kbytes in advance. This patch will throttle direct reclaimers
> > if half the PF_MEMALLOC reserves are in use as the system is at risk of
> > hanging. A message will be displayed so the administrator knows that
> > min_free_kbytes should be tuned to a higher value to avoid the
> > throttling in the future.
> >
>
> (I knew there was something else).
>
> I understand that there are suggestions that direct reclaim should always be
> serialised as this reduces lock contention and improve data patterns (or
> something like that).
>
AFAIK, this suggestion never got much beyond the "hand-waving" stage
of development. It tended to trip up on the fact that such a feature
could also throttle processes on machines with plenty of free clean
unmapped pagecache which would be undesirable.
> Would that make this patch redundant?
Depends on how it was being serialised but ....
> Or does this provide some extra
> guarantee that the other proposal would not?
>
This patch could be extended to serialise direct reclaims in situations
other than PFMEMALLOC is low if someone demonstrated the benefit.
--
Mel Gorman
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 38+ messages in thread
end of thread, other threads:[~2011-04-18 14:08 UTC | newest]
Thread overview: 38+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-04-14 10:41 [PATCH 00/12] Swap-over-NBD without deadlocking v1 Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 01/12] mm: Serialize access to min_free_kbytes Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 02/12] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 03/12] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 04/12] mm: allow PF_MEMALLOC from softirq context Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 05/12] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 06/12] net: Introduce sk_allocation() to allow addition of GFP flags depending on the individual socket Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 07/12] netvm: Allow the use of __GFP_MEMALLOC by specific sockets Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 08/12] netvm: Allow skb allocation to use PFMEMALLOC reserves Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 21:33 ` David Miller
2011-04-14 21:33 ` David Miller
2011-04-15 10:44 ` Mel Gorman
2011-04-15 10:44 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 09/12] netvm: Set PF_MEMALLOC as appropriate during SKB processing Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 10/12] mm: Micro-optimise slab to avoid a function call Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 11/12] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-14 10:41 ` [PATCH 12/12] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage Mel Gorman
2011-04-14 10:41 ` Mel Gorman
2011-04-18 12:30 ` NeilBrown
2011-04-18 12:30 ` NeilBrown
2011-04-18 14:04 ` Mel Gorman
2011-04-18 14:04 ` Mel Gorman
2011-04-18 12:32 ` NeilBrown
2011-04-18 12:32 ` NeilBrown
2011-04-18 14:08 ` Mel Gorman
2011-04-18 14:08 ` Mel Gorman
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