Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast

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* Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
@ 2022-09-13 13:09 yong
  2022-09-13 13:54 ` Greg KH
  0 siblings, 1 reply; 24+ messages in thread
From: yong @ 2022-09-13 13:09 UTC (permalink / raw)
  To: jaewon31.kim, gregkh, mhocko; +Cc: linux-kernel, stable, wang.yong12

Hello,
This patch is required to be patched in linux-5.4.y and linux-4.19.y.

In addition to that, the following two patches are somewhat related:

	3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
	9282012 page_alloc: fix invalid watermark check on a negative value

thanks.
	
	


^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
  2022-09-13 13:09 [PATCH v4] page_alloc: consider highatomic reserve in watermark fast yong
@ 2022-09-13 13:54 ` Greg KH
  2022-09-14  0:46   ` yong w
  0 siblings, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-09-13 13:54 UTC (permalink / raw)
  To: yong; +Cc: jaewon31.kim, mhocko, linux-kernel, stable, wang.yong12

On Tue, Sep 13, 2022 at 09:09:47PM +0800, yong wrote:
> Hello,
> This patch is required to be patched in linux-5.4.y and linux-4.19.y.

What is "this patch"?  There is no context here :(

> In addition to that, the following two patches are somewhat related:
> 
> 	3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
> 	9282012 page_alloc: fix invalid watermark check on a negative value

In what way?  What should be done here by us?

confused,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
  2022-09-13 13:54 ` Greg KH
@ 2022-09-14  0:46   ` yong w
  2022-09-16  9:40     ` Greg KH
       [not found]     ` <CGME20220916094017epcas1p1deed4041f897d2bf0e0486554d79b3af@epcms1p4>
  0 siblings, 2 replies; 24+ messages in thread
From: yong w @ 2022-09-14  0:46 UTC (permalink / raw)
  To: Greg KH; +Cc: jaewon31.kim, mhocko, linux-kernel, stable, wang.yong12

Greg KH <gregkh@linuxfoundation.org> 于2022年9月13日周二 21:54写道：

>
> On Tue, Sep 13, 2022 at 09:09:47PM +0800, yong wrote:
> > Hello,
> > This patch is required to be patched in linux-5.4.y and linux-4.19.y.
>
> What is "this patch"?  There is no context here :(
>
Sorry, I forgot to quote the original patch. the patch is as follows

    f27ce0e page_alloc: consider highatomic reserve in watermark fast

> > In addition to that, the following two patches are somewhat related:
> >
> >       3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
> >       9282012 page_alloc: fix invalid watermark check on a negative value
>
> In what way?  What should be done here by us?
>

I think these two patches should also be merged.

    The classzone_idx  parameter is used in the zone_watermark_fast
functionzone, and 3334a45 use ac->high_zoneidx for classzone_idx.
    "9282012 page_alloc: fix invalid watermark check on a negative
value"  fix f27ce0e introduced issues


> confused,
>
> greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
  2022-09-14  0:46   ` yong w
@ 2022-09-16  9:40     ` Greg KH
  2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
       [not found]     ` <CGME20220916094017epcas1p1deed4041f897d2bf0e0486554d79b3af@epcms1p4>
  1 sibling, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-09-16  9:40 UTC (permalink / raw)
  To: yong w; +Cc: jaewon31.kim, mhocko, linux-kernel, stable, wang.yong12

On Wed, Sep 14, 2022 at 08:46:15AM +0800, yong w wrote:
> Greg KH <gregkh@linuxfoundation.org> 于2022年9月13日周二 21:54写道：
> 
> >
> > On Tue, Sep 13, 2022 at 09:09:47PM +0800, yong wrote:
> > > Hello,
> > > This patch is required to be patched in linux-5.4.y and linux-4.19.y.
> >
> > What is "this patch"?  There is no context here :(
> >
> Sorry, I forgot to quote the original patch. the patch is as follows
> 
>     f27ce0e page_alloc: consider highatomic reserve in watermark fast
> 
> > > In addition to that, the following two patches are somewhat related:
> > >
> > >       3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
> > >       9282012 page_alloc: fix invalid watermark check on a negative value
> >
> > In what way?  What should be done here by us?
> >
> 
> I think these two patches should also be merged.
> 
>     The classzone_idx  parameter is used in the zone_watermark_fast
> functionzone, and 3334a45 use ac->high_zoneidx for classzone_idx.
>     "9282012 page_alloc: fix invalid watermark check on a negative
> value"  fix f27ce0e introduced issues

Ok, I need an ack by all the developers involved in those commits, as
well as the subsystem maintainer so that I know it's ok to take them.

Can you provide a series of backported and tested patches so that they
are easy to review?

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-09-16  9:40     ` Greg KH
@ 2022-09-16 17:05       ` wangyong
  2022-09-16 17:05         ` [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
                           ` (3 more replies)
  0 siblings, 4 replies; 24+ messages in thread
From: wangyong @ 2022-09-16 17:05 UTC (permalink / raw)
  To: gregkh; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12, yongw.pur

Here are the corresponding backports to 4.19.
And fix classzone_idx context differences causing patch merge conflicts.

Jaewon Kim (2):
  page_alloc: consider highatomic reserve in watermark fast
  page_alloc: fix invalid watermark check on a negative value

Joonsoo Kim (1):
  mm/page_alloc: use ac->high_zoneidx for classzone_idx

 mm/internal.h   |  2 +-
 mm/page_alloc.c | 69 +++++++++++++++++++++++++++++++++------------------------
 2 files changed, 41 insertions(+), 30 deletions(-)

-- 
2.7.4


^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
@ 2022-09-16 17:05         ` wangyong
  2022-09-16 17:09           ` kernel test robot
  2022-09-16 17:05         ` [PATCH 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
                           ` (2 subsequent siblings)
  3 siblings, 1 reply; 24+ messages in thread
From: wangyong @ 2022-09-16 17:05 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Joonsoo Kim, Andrew Morton, Johannes Weiner,
	Minchan Kim, Mel Gorman, Linus Torvalds

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Patch series "integrate classzone_idx and high_zoneidx", v5.

This patchset is followup of the problem reported and discussed two years
ago [1, 2].  The problem this patchset solves is related to the
classzone_idx on the NUMA system.  It causes a problem when the lowmem
reserve protection exists for some zones on a node that do not exist on
other nodes.

This problem was reported two years ago, and, at that time, the solution
got general agreements [2].  But it was not upstreamed.

[1]: http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop
[2]: http://lkml.kernel.org/r/1525408246-14768-1-git-send-email-iamjoonsoo.kim@lge.com

This patch (of 2):

Currently, we use classzone_idx to calculate lowmem reserve proetection
for an allocation request.  This classzone_idx causes a problem on NUMA
systems when the lowmem reserve protection exists for some zones on a node
that do not exist on other nodes.

Before further explanation, I should first clarify how to compute the
classzone_idx and the high_zoneidx.

- ac->high_zoneidx is computed via the arcane gfp_zone(gfp_mask) and
  represents the index of the highest zone the allocation can use

- classzone_idx was supposed to be the index of the highest zone on the
  local node that the allocation can use, that is actually available in
  the system

Think about following example.  Node 0 has 4 populated zone,
DMA/DMA32/NORMAL/MOVABLE.  Node 1 has 1 populated zone, NORMAL.  Some
zones, such as MOVABLE, doesn't exist on node 1 and this makes following
difference.

Assume that there is an allocation request whose gfp_zone(gfp_mask) is the
zone, MOVABLE.  Then, it's high_zoneidx is 3.  If this allocation is
initiated on node 0, it's classzone_idx is 3 since actually
available/usable zone on local (node 0) is MOVABLE.  If this allocation is
initiated on node 1, it's classzone_idx is 2 since actually
available/usable zone on local (node 1) is NORMAL.

You can see that classzone_idx of the allocation request are different
according to their starting node, even if their high_zoneidx is the same.

Think more about these two allocation requests.  If they are processed on
local, there is no problem.  However, if allocation is initiated on node 1
are processed on remote, in this example, at the NORMAL zone on node 0,
due to memory shortage, problem occurs.  Their different classzone_idx
leads to different lowmem reserve and then different min watermark.  See
the following example.

root@ubuntu:/sys/devices/system/memory# cat /proc/zoneinfo
Node 0, zone      DMA
  per-node stats
...
  pages free     3965
        min      5
        low      8
        high     11
        spanned  4095
        present  3998
        managed  3977
        protection: (0, 2961, 4928, 5440)
...
Node 0, zone    DMA32
  pages free     757955
        min      1129
        low      1887
        high     2645
        spanned  1044480
        present  782303
        managed  758116
        protection: (0, 0, 1967, 2479)
...
Node 0, zone   Normal
  pages free     459806
        min      750
        low      1253
        high     1756
        spanned  524288
        present  524288
        managed  503620
        protection: (0, 0, 0, 4096)
...
Node 0, zone  Movable
  pages free     130759
        min      195
        low      326
        high     457
        spanned  1966079
        present  131072
        managed  131072
        protection: (0, 0, 0, 0)
...
Node 1, zone      DMA
  pages free     0
        min      0
        low      0
        high     0
        spanned  0
        present  0
        managed  0
        protection: (0, 0, 1006, 1006)
Node 1, zone    DMA32
  pages free     0
        min      0
        low      0
        high     0
        spanned  0
        present  0
        managed  0
        protection: (0, 0, 1006, 1006)
Node 1, zone   Normal
  per-node stats
...
  pages free     233277
        min      383
        low      640
        high     897
        spanned  262144
        present  262144
        managed  257744
        protection: (0, 0, 0, 0)
...
Node 1, zone  Movable
  pages free     0
        min      0
        low      0
        high     0
        spanned  262144
        present  0
        managed  0
        protection: (0, 0, 0, 0)

- static min watermark for the NORMAL zone on node 0 is 750.

- lowmem reserve for the request with classzone idx 3 at the NORMAL on
  node 0 is 4096.

- lowmem reserve for the request with classzone idx 2 at the NORMAL on
  node 0 is 0.

So, overall min watermark is:
allocation initiated on node 0 (classzone_idx 3): 750 + 4096 = 4846
allocation initiated on node 1 (classzone_idx 2): 750 + 0 = 750

Allocation initiated on node 1 will have some precedence than allocation
initiated on node 0 because min watermark of the former allocation is
lower than the other.  So, allocation initiated on node 1 could succeed on
node 0 when allocation initiated on node 0 could not, and, this could
cause too many numa_miss allocation.  Then, performance could be
downgraded.

Recently, there was a regression report about this problem on CMA patches
since CMA memory are placed in ZONE_MOVABLE by those patches.  I checked
that problem is disappeared with this fix that uses high_zoneidx for
classzone_idx.

http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop

Using high_zoneidx for classzone_idx is more consistent way than previous
approach because system's memory layout doesn't affect anything to it.
With this patch, both classzone_idx on above example will be 3 so will
have the same min watermark.

allocation initiated on node 0: 750 + 4096 = 4846
allocation initiated on node 1: 750 + 4096 = 4846

One could wonder if there is a side effect that allocation initiated on
node 1 will use higher bar when allocation is handled on local since
classzone_idx could be higher than before.  It will not happen because the
zone without managed page doesn't contributes lowmem_reserve at all.

Reported-by: Ye Xiaolong <xiaolong.ye@intel.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Ye Xiaolong <xiaolong.ye@intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Link: http://lkml.kernel.org/r/1587095923-7515-1-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1587095923-7515-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/internal.h b/mm/internal.h
index 3a2e973..922a173 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -123,7 +123,7 @@ struct alloc_context {
 	bool spread_dirty_pages;
 };

-#define ac_classzone_idx(ac) zonelist_zone_idx(ac->preferred_zoneref)
+#define ac_classzone_idx(ac) (ac->high_zoneidx)

 /*
  * Locate the struct page for both the matching buddy in our
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 24+ messages in thread

* Re: [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-16 17:05         ` [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
@ 2022-09-16 17:09           ` kernel test robot
  0 siblings, 0 replies; 24+ messages in thread
From: kernel test robot @ 2022-09-16 17:09 UTC (permalink / raw)
  To: wangyong; +Cc: stable, kbuild-all

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

Rule: 'Cc: stable@vger.kernel.org' or 'commit <sha1> upstream.'
Subject: [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
Link: https://lore.kernel.org/stable/1663347949-20389-2-git-send-email-wang.yong12%40zte.com.cn

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp




^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH 2/3] page_alloc: consider highatomic reserve in watermark fast
  2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
  2022-09-16 17:05         ` [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
@ 2022-09-16 17:05         ` wangyong
  2022-09-16 17:05         ` [PATCH 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
  2022-09-20 17:41         ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
  3 siblings, 0 replies; 24+ messages in thread
From: wangyong @ 2022-09-16 17:05 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Andrew Morton, Johannes Weiner, Yong-Taek Lee,
	Linus Torvalds

From: Jaewon Kim <jaewon31.kim@samsung.com>

zone_watermark_fast was introduced by commit 48ee5f3696f6 ("mm,
page_alloc: shortcut watermark checks for order-0 pages").  The commit
simply checks if free pages is bigger than watermark without additional
calculation such like reducing watermark.

It considered free cma pages but it did not consider highatomic reserved.
This may incur exhaustion of free pages except high order atomic free
pages.

Assume that reserved_highatomic pageblock is bigger than watermark min,
and there are only few free pages except high order atomic free.  Because
zone_watermark_fast passes the allocation without considering high order
atomic free, normal reclaimable allocation like GFP_HIGHUSER will consume
all the free pages.  Then finally order-0 atomic allocation may fail on
allocation.

This means watermark min is not protected against non-atomic allocation.
The order-0 atomic allocation with ALLOC_HARDER unwantedly can be failed.
Additionally the __GFP_MEMALLOC allocation with ALLOC_NO_WATERMARKS also
can be failed.

To avoid the problem, zone_watermark_fast should consider highatomic
reserve.  If the actual size of high atomic free is counted accurately
like cma free, we may use it.  On this patch just use
nr_reserved_highatomic.  Additionally introduce
__zone_watermark_unusable_free to factor out common parts between
zone_watermark_fast and __zone_watermark_ok.

This is an example of ALLOC_HARDER allocation failure using v4.19 based
kernel.

 Binder:9343_3: page allocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=(null)
 Call trace:
 [<ffffff8008f40f8c>] dump_stack+0xb8/0xf0
 [<ffffff8008223320>] warn_alloc+0xd8/0x12c
 [<ffffff80082245e4>] __alloc_pages_nodemask+0x120c/0x1250
 [<ffffff800827f6e8>] new_slab+0x128/0x604
 [<ffffff800827b0cc>] ___slab_alloc+0x508/0x670
 [<ffffff800827ba00>] __kmalloc+0x2f8/0x310
 [<ffffff80084ac3e0>] context_struct_to_string+0x104/0x1cc
 [<ffffff80084ad8fc>] security_sid_to_context_core+0x74/0x144
 [<ffffff80084ad880>] security_sid_to_context+0x10/0x18
 [<ffffff800849bd80>] selinux_secid_to_secctx+0x20/0x28
 [<ffffff800849109c>] security_secid_to_secctx+0x3c/0x70
 [<ffffff8008bfe118>] binder_transaction+0xe68/0x454c
 Mem-Info:
 active_anon:102061 inactive_anon:81551 isolated_anon:0
  active_file:59102 inactive_file:68924 isolated_file:64
  unevictable:611 dirty:63 writeback:0 unstable:0
  slab_reclaimable:13324 slab_unreclaimable:44354
  mapped:83015 shmem:4858 pagetables:26316 bounce:0
  free:2727 free_pcp:1035 free_cma:178
 Node 0 active_anon:408244kB inactive_anon:326204kB active_file:236408kB inactive_file:275696kB unevictable:2444kB isolated(anon):0kB isolated(file):256kB mapped:332060kB dirty:252kB writeback:0kB shmem:19432kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
 Normal free:10908kB min:6192kB low:44388kB high:47060kB active_anon:409160kB inactive_anon:325924kB active_file:235820kB inactive_file:276628kB unevictable:2444kB writepending:252kB present:3076096kB managed:2673676kB mlocked:2444kB kernel_stack:62512kB pagetables:105264kB bounce:0kB free_pcp:4140kB local_pcp:40kB free_cma:712kB
 lowmem_reserve[]: 0 0
 Normal: 505*4kB (H) 357*8kB (H) 201*16kB (H) 65*32kB (H) 1*64kB (H) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 10236kB
 138826 total pagecache pages
 5460 pages in swap cache
 Swap cache stats: add 8273090, delete 8267506, find 1004381/4060142

This is an example of ALLOC_NO_WATERMARKS allocation failure using v4.14
based kernel.

 kswapd0: page allocation failure: order:0, mode:0x140000a(GFP_NOIO|__GFP_HIGHMEM|__GFP_MOVABLE), nodemask=(null)
 kswapd0 cpuset=/ mems_allowed=0
 CPU: 4 PID: 1221 Comm: kswapd0 Not tainted 4.14.113-18770262-userdebug #1
 Call trace:
 [<0000000000000000>] dump_backtrace+0x0/0x248
 [<0000000000000000>] show_stack+0x18/0x20
 [<0000000000000000>] __dump_stack+0x20/0x28
 [<0000000000000000>] dump_stack+0x68/0x90
 [<0000000000000000>] warn_alloc+0x104/0x198
 [<0000000000000000>] __alloc_pages_nodemask+0xdc0/0xdf0
 [<0000000000000000>] zs_malloc+0x148/0x3d0
 [<0000000000000000>] zram_bvec_rw+0x410/0x798
 [<0000000000000000>] zram_rw_page+0x88/0xdc
 [<0000000000000000>] bdev_write_page+0x70/0xbc
 [<0000000000000000>] __swap_writepage+0x58/0x37c
 [<0000000000000000>] swap_writepage+0x40/0x4c
 [<0000000000000000>] shrink_page_list+0xc30/0xf48
 [<0000000000000000>] shrink_inactive_list+0x2b0/0x61c
 [<0000000000000000>] shrink_node_memcg+0x23c/0x618
 [<0000000000000000>] shrink_node+0x1c8/0x304
 [<0000000000000000>] kswapd+0x680/0x7c4
 [<0000000000000000>] kthread+0x110/0x120
 [<0000000000000000>] ret_from_fork+0x10/0x18
 Mem-Info:
 active_anon:111826 inactive_anon:65557 isolated_anon:0\x0a active_file:44260 inactive_file:83422 isolated_file:0\x0a unevictable:4158 dirty:117 writeback:0 unstable:0\x0a            slab_reclaimable:13943 slab_unreclaimable:43315\x0a mapped:102511 shmem:3299 pagetables:19566 bounce:0\x0a free:3510 free_pcp:553 free_cma:0
 Node 0 active_anon:447304kB inactive_anon:262228kB active_file:177040kB inactive_file:333688kB unevictable:16632kB isolated(anon):0kB isolated(file):0kB mapped:410044kB d irty:468kB writeback:0kB shmem:13196kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
 Normal free:14040kB min:7440kB low:94500kB high:98136kB reserved_highatomic:32768KB active_anon:447336kB inactive_anon:261668kB active_file:177572kB inactive_file:333768k           B unevictable:16632kB writepending:480kB present:4081664kB managed:3637088kB mlocked:16632kB kernel_stack:47072kB pagetables:78264kB bounce:0kB free_pcp:2280kB local_pcp:720kB free_cma:0kB        [ 4738.329607] lowmem_reserve[]: 0 0
 Normal: 860*4kB (H) 453*8kB (H) 180*16kB (H) 26*32kB (H) 34*64kB (H) 6*128kB (H) 2*256kB (H) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 14232kB

This is trace log which shows GFP_HIGHUSER consumes free pages right
before ALLOC_NO_WATERMARKS.

  <...>-22275 [006] ....   889.213383: mm_page_alloc: page=00000000d2be5665 pfn=970744 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213385: mm_page_alloc: page=000000004b2335c2 pfn=970745 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213387: mm_page_alloc: page=00000000017272e1 pfn=970278 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213389: mm_page_alloc: page=00000000c4be79fb pfn=970279 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213391: mm_page_alloc: page=00000000f8a51d4f pfn=970260 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213393: mm_page_alloc: page=000000006ba8f5ac pfn=970261 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213395: mm_page_alloc: page=00000000819f1cd3 pfn=970196 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213396: mm_page_alloc: page=00000000f6b72a64 pfn=970197 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
kswapd0-1207  [005] ...1   889.213398: mm_page_alloc: page= (null) pfn=0 order=0 migratetype=1 nr_free=3650 gfp_flags=GFP_NOWAIT|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_MOVABLE

[jaewon31.kim@samsung.com: remove redundant code for high-order]
  Link: http://lkml.kernel.org/r/20200623035242.27232-1-jaewon31.kim@samsung.com

Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20200619235958.11283-1-jaewon31.kim@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/page_alloc.c | 65 ++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9c35403..237463d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3130,6 +3130,29 @@ static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
 
 #endif /* CONFIG_FAIL_PAGE_ALLOC */
 
+static inline long __zone_watermark_unusable_free(struct zone *z,
+				unsigned int order, unsigned int alloc_flags)
+{
+	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
+	long unusable_free = (1 << order) - 1;
+
+	/*
+	 * If the caller does not have rights to ALLOC_HARDER then subtract
+	 * the high-atomic reserves. This will over-estimate the size of the
+	 * atomic reserve but it avoids a search.
+	 */
+	if (likely(!alloc_harder))
+		unusable_free += z->nr_reserved_highatomic;
+
+#ifdef CONFIG_CMA
+	/* If allocation can't use CMA areas don't use free CMA pages */
+	if (!(alloc_flags & ALLOC_CMA))
+		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
+
+	return unusable_free;
+}
+
 /*
  * Return true if free base pages are above 'mark'. For high-order checks it
  * will return true of the order-0 watermark is reached and there is at least
@@ -3145,19 +3168,12 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
 
 	/* free_pages may go negative - that's OK */
-	free_pages -= (1 << order) - 1;
+	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
 
 	if (alloc_flags & ALLOC_HIGH)
 		min -= min / 2;
 
-	/*
-	 * If the caller does not have rights to ALLOC_HARDER then subtract
-	 * the high-atomic reserves. This will over-estimate the size of the
-	 * atomic reserve but it avoids a search.
-	 */
-	if (likely(!alloc_harder)) {
-		free_pages -= z->nr_reserved_highatomic;
-	} else {
+	if (unlikely(alloc_harder)) {
 		/*
 		 * OOM victims can try even harder than normal ALLOC_HARDER
 		 * users on the grounds that it's definitely going to be in
@@ -3170,13 +3186,6 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 			min -= min / 4;
 	}
 
-
-#ifdef CONFIG_CMA
-	/* If allocation can't use CMA areas don't use free CMA pages */
-	if (!(alloc_flags & ALLOC_CMA))
-		free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
-#endif
-
 	/*
 	 * Check watermarks for an order-0 allocation request. If these
 	 * are not met, then a high-order request also cannot go ahead
@@ -3225,24 +3234,22 @@ bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
 		unsigned long mark, int classzone_idx, unsigned int alloc_flags)
 {
-	long free_pages = zone_page_state(z, NR_FREE_PAGES);
-	long cma_pages = 0;
+	long free_pages;
 
-#ifdef CONFIG_CMA
-	/* If allocation can't use CMA areas don't use free CMA pages */
-	if (!(alloc_flags & ALLOC_CMA))
-		cma_pages = zone_page_state(z, NR_FREE_CMA_PAGES);
-#endif
+	free_pages = zone_page_state(z, NR_FREE_PAGES);
 
 	/*
 	 * Fast check for order-0 only. If this fails then the reserves
-	 * need to be calculated. There is a corner case where the check
-	 * passes but only the high-order atomic reserve are free. If
-	 * the caller is !atomic then it'll uselessly search the free
-	 * list. That corner case is then slower but it is harmless.
+	 * need to be calculated.
 	 */
-	if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserve[classzone_idx])
-		return true;
+	if (!order) {
+		long fast_free;
+
+		fast_free = free_pages;
+		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
+		if (fast_free > mark + z->lowmem_reserve[classzone_idx])
+			return true;
+	}
 
 	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
 					free_pages);
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 24+ messages in thread

* [PATCH 3/3] page_alloc: fix invalid watermark check on a negative value
  2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
  2022-09-16 17:05         ` [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
  2022-09-16 17:05         ` [PATCH 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
@ 2022-09-16 17:05         ` wangyong
  2022-09-20 17:41         ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
  3 siblings, 0 replies; 24+ messages in thread
From: wangyong @ 2022-09-16 17:05 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Minchan Kim, Baoquan He, Vlastimil Babka,
	Johannes Weiner, Yong-Taek Lee, stable, Andrew Morton

From: Jaewon Kim <jaewon31.kim@samsung.com>

There was a report that a task is waiting at the
throttle_direct_reclaim. The pgscan_direct_throttle in vmstat was
increasing.

This is a bug where zone_watermark_fast returns true even when the free
is very low. The commit f27ce0e14088 ("page_alloc: consider highatomic
reserve in watermark fast") changed the watermark fast to consider
highatomic reserve. But it did not handle a negative value case which
can be happened when reserved_highatomic pageblock is bigger than the
actual free.

If watermark is considered as ok for the negative value, allocating
contexts for order-0 will consume all free pages without direct reclaim,
and finally free page may become depleted except highatomic free.

Then allocating contexts may fall into throttle_direct_reclaim. This
symptom may easily happen in a system where wmark min is low and other
reclaimers like kswapd does not make free pages quickly.

Handle the negative case by using MIN.

Link: https://lkml.kernel.org/r/20220725095212.25388-1-jaewon31.kim@samsung.com
Fixes: f27ce0e14088 ("page_alloc: consider highatomic reserve in watermark fast")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: GyeongHwan Hong <gh21.hong@samsung.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kerenl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_alloc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 237463d..d6d8a37 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3243,11 +3243,15 @@ static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
 	 * need to be calculated.
 	 */
 	if (!order) {
-		long fast_free;
+		long usable_free;
+		long reserved;
 
-		fast_free = free_pages;
-		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
-		if (fast_free > mark + z->lowmem_reserve[classzone_idx])
+		usable_free = free_pages;
+		reserved = __zone_watermark_unusable_free(z, 0, alloc_flags);
+
+		/* reserved may over estimate high-atomic reserves. */
+		usable_free -= min(usable_free, reserved);
+		if (usable_free > mark + z->lowmem_reserve[classzone_idx])
 			return true;
 	}
 
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 24+ messages in thread

* Re: [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
                           ` (2 preceding siblings ...)
  2022-09-16 17:05         ` [PATCH 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
@ 2022-09-20 17:41         ` Greg KH
  2022-09-25 10:35           ` [PATCH v2 " wangyong
  3 siblings, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-09-20 17:41 UTC (permalink / raw)
  To: wangyong; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12

On Fri, Sep 16, 2022 at 10:05:46AM -0700, wangyong wrote:
> Here are the corresponding backports to 4.19.
> And fix classzone_idx context differences causing patch merge conflicts.
> 
> Jaewon Kim (2):
>   page_alloc: consider highatomic reserve in watermark fast
>   page_alloc: fix invalid watermark check on a negative value
> 
> Joonsoo Kim (1):
>   mm/page_alloc: use ac->high_zoneidx for classzone_idx
> 
>  mm/internal.h   |  2 +-
>  mm/page_alloc.c | 69 +++++++++++++++++++++++++++++++++------------------------
>  2 files changed, 41 insertions(+), 30 deletions(-)
> 
> -- 
> 2.7.4
> 

What are the git commit ids of these commits?  That needs to be in the
commit changelog.

Also you did not sign off on the backports, please fix that up when you
resend this series.

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-09-20 17:41         ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
@ 2022-09-25 10:35           ` wangyong
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
                               ` (3 more replies)
  0 siblings, 4 replies; 24+ messages in thread
From: wangyong @ 2022-09-25 10:35 UTC (permalink / raw)
  To: gregkh; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12, yongw.pur

Here are the corresponding backports to 4.19.
And fix classzone_idx context differences causing patch merge conflicts.

Original commit IDS:
	3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
	f27ce0e page_alloc: consider highatomic reserve in watermark fast
	9282012 page_alloc: fix invalid watermark check on a negative value

Changes from v1:
- Add commit information of the original patches.

Jaewon Kim (2):
  page_alloc: consider highatomic reserve in watermark fast
  page_alloc: fix invalid watermark check on a negative value

Joonsoo Kim (1):
  mm/page_alloc: use ac->high_zoneidx for classzone_idx

 mm/internal.h   |  2 +-
 mm/page_alloc.c | 69 +++++++++++++++++++++++++++++++++------------------------
 2 files changed, 41 insertions(+), 30 deletions(-)

-- 
2.7.4

^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-25 10:35           ` [PATCH v2 " wangyong
@ 2022-09-25 10:35             ` wangyong
  2022-09-25 10:36               ` kernel test robot
  2022-09-25 11:00               ` Greg KH
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
                               ` (2 subsequent siblings)
  3 siblings, 2 replies; 24+ messages in thread
From: wangyong @ 2022-09-25 10:35 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Joonsoo Kim, Andrew Morton, Johannes Weiner,
	Minchan Kim, Mel Gorman, Linus Torvalds

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

[ backport of commit 3334a45eb9e2bb040c880ef65e1d72357a0a008b ]

Patch series "integrate classzone_idx and high_zoneidx", v5.

This patchset is followup of the problem reported and discussed two years
ago [1, 2].  The problem this patchset solves is related to the
classzone_idx on the NUMA system.  It causes a problem when the lowmem
reserve protection exists for some zones on a node that do not exist on
other nodes.

This problem was reported two years ago, and, at that time, the solution
got general agreements [2].  But it was not upstreamed.

[1]: http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop
[2]: http://lkml.kernel.org/r/1525408246-14768-1-git-send-email-iamjoonsoo.kim@lge.com

This patch (of 2):

Currently, we use classzone_idx to calculate lowmem reserve proetection
for an allocation request.  This classzone_idx causes a problem on NUMA
systems when the lowmem reserve protection exists for some zones on a node
that do not exist on other nodes.

Before further explanation, I should first clarify how to compute the
classzone_idx and the high_zoneidx.

- ac->high_zoneidx is computed via the arcane gfp_zone(gfp_mask) and
  represents the index of the highest zone the allocation can use

- classzone_idx was supposed to be the index of the highest zone on the
  local node that the allocation can use, that is actually available in
  the system

Think about following example.  Node 0 has 4 populated zone,
DMA/DMA32/NORMAL/MOVABLE.  Node 1 has 1 populated zone, NORMAL.  Some
zones, such as MOVABLE, doesn't exist on node 1 and this makes following
difference.

Assume that there is an allocation request whose gfp_zone(gfp_mask) is the
zone, MOVABLE.  Then, it's high_zoneidx is 3.  If this allocation is
initiated on node 0, it's classzone_idx is 3 since actually
available/usable zone on local (node 0) is MOVABLE.  If this allocation is
initiated on node 1, it's classzone_idx is 2 since actually
available/usable zone on local (node 1) is NORMAL.

You can see that classzone_idx of the allocation request are different
according to their starting node, even if their high_zoneidx is the same.

Think more about these two allocation requests.  If they are processed on
local, there is no problem.  However, if allocation is initiated on node 1
are processed on remote, in this example, at the NORMAL zone on node 0,
due to memory shortage, problem occurs.  Their different classzone_idx
leads to different lowmem reserve and then different min watermark.  See
the following example.

root@ubuntu:/sys/devices/system/memory# cat /proc/zoneinfo
Node 0, zone      DMA
  per-node stats
...
  pages free     3965
        min      5
        low      8
        high     11
        spanned  4095
        present  3998
        managed  3977
        protection: (0, 2961, 4928, 5440)
...
Node 0, zone    DMA32
  pages free     757955
        min      1129
        low      1887
        high     2645
        spanned  1044480
        present  782303
        managed  758116
        protection: (0, 0, 1967, 2479)
...
Node 0, zone   Normal
  pages free     459806
        min      750
        low      1253
        high     1756
        spanned  524288
        present  524288
        managed  503620
        protection: (0, 0, 0, 4096)
...
Node 0, zone  Movable
  pages free     130759
        min      195
        low      326
        high     457
        spanned  1966079
        present  131072
        managed  131072
        protection: (0, 0, 0, 0)
...
Node 1, zone      DMA
  pages free     0
        min      0
        low      0
        high     0
        spanned  0
        present  0
        managed  0
        protection: (0, 0, 1006, 1006)
Node 1, zone    DMA32
  pages free     0
        min      0
        low      0
        high     0
        spanned  0
        present  0
        managed  0
        protection: (0, 0, 1006, 1006)
Node 1, zone   Normal
  per-node stats
...
  pages free     233277
        min      383
        low      640
        high     897
        spanned  262144
        present  262144
        managed  257744
        protection: (0, 0, 0, 0)
...
Node 1, zone  Movable
  pages free     0
        min      0
        low      0
        high     0
        spanned  262144
        present  0
        managed  0
        protection: (0, 0, 0, 0)

- static min watermark for the NORMAL zone on node 0 is 750.

- lowmem reserve for the request with classzone idx 3 at the NORMAL on
  node 0 is 4096.

- lowmem reserve for the request with classzone idx 2 at the NORMAL on
  node 0 is 0.

So, overall min watermark is:
allocation initiated on node 0 (classzone_idx 3): 750 + 4096 = 4846
allocation initiated on node 1 (classzone_idx 2): 750 + 0 = 750

Allocation initiated on node 1 will have some precedence than allocation
initiated on node 0 because min watermark of the former allocation is
lower than the other.  So, allocation initiated on node 1 could succeed on
node 0 when allocation initiated on node 0 could not, and, this could
cause too many numa_miss allocation.  Then, performance could be
downgraded.

Recently, there was a regression report about this problem on CMA patches
since CMA memory are placed in ZONE_MOVABLE by those patches.  I checked
that problem is disappeared with this fix that uses high_zoneidx for
classzone_idx.

http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop

Using high_zoneidx for classzone_idx is more consistent way than previous
approach because system's memory layout doesn't affect anything to it.
With this patch, both classzone_idx on above example will be 3 so will
have the same min watermark.

allocation initiated on node 0: 750 + 4096 = 4846
allocation initiated on node 1: 750 + 4096 = 4846

One could wonder if there is a side effect that allocation initiated on
node 1 will use higher bar when allocation is handled on local since
classzone_idx could be higher than before.  It will not happen because the
zone without managed page doesn't contributes lowmem_reserve at all.

Reported-by: Ye Xiaolong <xiaolong.ye@intel.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Ye Xiaolong <xiaolong.ye@intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Link: http://lkml.kernel.org/r/1587095923-7515-1-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1587095923-7515-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/internal.h b/mm/internal.h
index 3a2e973..922a173 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -123,7 +123,7 @@ struct alloc_context {
 	bool spread_dirty_pages;
 };

-#define ac_classzone_idx(ac) zonelist_zone_idx(ac->preferred_zoneref)
+#define ac_classzone_idx(ac) (ac->high_zoneidx)

 /*
  * Locate the struct page for both the matching buddy in our
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
@ 2022-09-25 10:36               ` kernel test robot
  2022-09-25 11:00               ` Greg KH
  1 sibling, 0 replies; 24+ messages in thread
From: kernel test robot @ 2022-09-25 10:36 UTC (permalink / raw)
  To: wangyong; +Cc: stable, kbuild-all

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

Rule: 'Cc: stable@vger.kernel.org' or 'commit <sha1> upstream.'
Subject: [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
Link: https://lore.kernel.org/stable/20220925103529.13716-2-yongw.pur%40gmail.com

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp




^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
  2022-09-25 10:36               ` kernel test robot
@ 2022-09-25 11:00               ` Greg KH
  2022-09-25 14:32                 ` yong w
  1 sibling, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-09-25 11:00 UTC (permalink / raw)
  To: wangyong
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	Joonsoo Kim, Andrew Morton, Johannes Weiner, Minchan Kim,
	Mel Gorman, Linus Torvalds

On Sun, Sep 25, 2022 at 03:35:27AM -0700, wangyong wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> [ backport of commit 3334a45eb9e2bb040c880ef65e1d72357a0a008b ]

This is from 5.8.  What about the 5.4.y kernel?  Why would someone
upgrading from 4.19.y to 5.4.y suffer a regression here?

And why wouldn't someone who has this issue just not use 5.10.y instead?
What prevents someone from moving off of 4.19.y at this point in time?

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-25 11:00               ` Greg KH
@ 2022-09-25 14:32                 ` yong w
  2022-09-26  6:46                   ` Greg KH
  0 siblings, 1 reply; 24+ messages in thread
From: yong w @ 2022-09-25 14:32 UTC (permalink / raw)
  To: Greg KH, jaewon31.kim
  Cc: linux-kernel, mhocko, stable, wang.yong12, Joonsoo Kim,
	Andrew Morton, Johannes Weiner, Minchan Kim, Mel Gorman,
	Linus Torvalds

Greg KH <gregkh@linuxfoundation.org> 于2022年9月25日周日 19:00写道：
>
> On Sun, Sep 25, 2022 at 03:35:27AM -0700, wangyong wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > [ backport of commit 3334a45eb9e2bb040c880ef65e1d72357a0a008b ]
>
> This is from 5.8.  What about the 5.4.y kernel?  Why would someone
> upgrading from 4.19.y to 5.4.y suffer a regression here?
>
I encountered this problem on 4.19, but I haven't encountered it on 5.4.
However, this should be a common problem, so 5.4 may also need to be
merged.

Hello, Joonsoo, what do you think?

> And why wouldn't someone who has this issue just not use 5.10.y instead?
> What prevents someone from moving off of 4.19.y at this point in time?
>
This is a solution, but upgrading the kernel version requires time and overhead,
so use the patch is the most effective way, if there is.

Thanks.
> thanks,
>
> greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx
  2022-09-25 14:32                 ` yong w
@ 2022-09-26  6:46                   ` Greg KH
  0 siblings, 0 replies; 24+ messages in thread
From: Greg KH @ 2022-09-26  6:46 UTC (permalink / raw)
  To: yong w
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	Joonsoo Kim, Andrew Morton, Johannes Weiner, Minchan Kim,
	Mel Gorman, Linus Torvalds

On Sun, Sep 25, 2022 at 10:32:32PM +0800, yong w wrote:
> Greg KH <gregkh@linuxfoundation.org> 于2022年9月25日周日 19:00写道：
> >
> > On Sun, Sep 25, 2022 at 03:35:27AM -0700, wangyong wrote:
> > > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > >
> > > [ backport of commit 3334a45eb9e2bb040c880ef65e1d72357a0a008b ]
> >
> > This is from 5.8.  What about the 5.4.y kernel?  Why would someone
> > upgrading from 4.19.y to 5.4.y suffer a regression here?
> >
> I encountered this problem on 4.19, but I haven't encountered it on 5.4.
> However, this should be a common problem, so 5.4 may also need to be
> merged.
> 
> Hello, Joonsoo, what do you think?
> 
> > And why wouldn't someone who has this issue just not use 5.10.y instead?
> > What prevents someone from moving off of 4.19.y at this point in time?
> >
> This is a solution, but upgrading the kernel version requires time and overhead,
> so use the patch is the most effective way, if there is.

You will have to move off of 4.19 soon anyway, so why delay the change?

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* [PATCH v2 stable-4.19 2/3] page_alloc: consider highatomic reserve in watermark fast
  2022-09-25 10:35           ` [PATCH v2 " wangyong
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
@ 2022-09-25 10:35             ` wangyong
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
  2022-10-02 15:37             ` [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
  3 siblings, 0 replies; 24+ messages in thread
From: wangyong @ 2022-09-25 10:35 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Andrew Morton, Johannes Weiner, Yong-Taek Lee,
	Linus Torvalds

From: Jaewon Kim <jaewon31.kim@samsung.com>

[ backport of commit f27ce0e14088b23f8d54ae4a44f70307ec420e64 ]

zone_watermark_fast was introduced by commit 48ee5f3696f6 ("mm,
page_alloc: shortcut watermark checks for order-0 pages").  The commit
simply checks if free pages is bigger than watermark without additional
calculation such like reducing watermark.

It considered free cma pages but it did not consider highatomic reserved.
This may incur exhaustion of free pages except high order atomic free
pages.

Assume that reserved_highatomic pageblock is bigger than watermark min,
and there are only few free pages except high order atomic free.  Because
zone_watermark_fast passes the allocation without considering high order
atomic free, normal reclaimable allocation like GFP_HIGHUSER will consume
all the free pages.  Then finally order-0 atomic allocation may fail on
allocation.

This means watermark min is not protected against non-atomic allocation.
The order-0 atomic allocation with ALLOC_HARDER unwantedly can be failed.
Additionally the __GFP_MEMALLOC allocation with ALLOC_NO_WATERMARKS also
can be failed.

To avoid the problem, zone_watermark_fast should consider highatomic
reserve.  If the actual size of high atomic free is counted accurately
like cma free, we may use it.  On this patch just use
nr_reserved_highatomic.  Additionally introduce
__zone_watermark_unusable_free to factor out common parts between
zone_watermark_fast and __zone_watermark_ok.

This is an example of ALLOC_HARDER allocation failure using v4.19 based
kernel.

 Binder:9343_3: page allocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=(null)
 Call trace:
 [<ffffff8008f40f8c>] dump_stack+0xb8/0xf0
 [<ffffff8008223320>] warn_alloc+0xd8/0x12c
 [<ffffff80082245e4>] __alloc_pages_nodemask+0x120c/0x1250
 [<ffffff800827f6e8>] new_slab+0x128/0x604
 [<ffffff800827b0cc>] ___slab_alloc+0x508/0x670
 [<ffffff800827ba00>] __kmalloc+0x2f8/0x310
 [<ffffff80084ac3e0>] context_struct_to_string+0x104/0x1cc
 [<ffffff80084ad8fc>] security_sid_to_context_core+0x74/0x144
 [<ffffff80084ad880>] security_sid_to_context+0x10/0x18
 [<ffffff800849bd80>] selinux_secid_to_secctx+0x20/0x28
 [<ffffff800849109c>] security_secid_to_secctx+0x3c/0x70
 [<ffffff8008bfe118>] binder_transaction+0xe68/0x454c
 Mem-Info:
 active_anon:102061 inactive_anon:81551 isolated_anon:0
  active_file:59102 inactive_file:68924 isolated_file:64
  unevictable:611 dirty:63 writeback:0 unstable:0
  slab_reclaimable:13324 slab_unreclaimable:44354
  mapped:83015 shmem:4858 pagetables:26316 bounce:0
  free:2727 free_pcp:1035 free_cma:178
 Node 0 active_anon:408244kB inactive_anon:326204kB active_file:236408kB inactive_file:275696kB unevictable:2444kB isolated(anon):0kB isolated(file):256kB mapped:332060kB dirty:252kB writeback:0kB shmem:19432kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
 Normal free:10908kB min:6192kB low:44388kB high:47060kB active_anon:409160kB inactive_anon:325924kB active_file:235820kB inactive_file:276628kB unevictable:2444kB writepending:252kB present:3076096kB managed:2673676kB mlocked:2444kB kernel_stack:62512kB pagetables:105264kB bounce:0kB free_pcp:4140kB local_pcp:40kB free_cma:712kB
 lowmem_reserve[]: 0 0
 Normal: 505*4kB (H) 357*8kB (H) 201*16kB (H) 65*32kB (H) 1*64kB (H) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 10236kB
 138826 total pagecache pages
 5460 pages in swap cache
 Swap cache stats: add 8273090, delete 8267506, find 1004381/4060142

This is an example of ALLOC_NO_WATERMARKS allocation failure using v4.14
based kernel.

 kswapd0: page allocation failure: order:0, mode:0x140000a(GFP_NOIO|__GFP_HIGHMEM|__GFP_MOVABLE), nodemask=(null)
 kswapd0 cpuset=/ mems_allowed=0
 CPU: 4 PID: 1221 Comm: kswapd0 Not tainted 4.14.113-18770262-userdebug #1
 Call trace:
 [<0000000000000000>] dump_backtrace+0x0/0x248
 [<0000000000000000>] show_stack+0x18/0x20
 [<0000000000000000>] __dump_stack+0x20/0x28
 [<0000000000000000>] dump_stack+0x68/0x90
 [<0000000000000000>] warn_alloc+0x104/0x198
 [<0000000000000000>] __alloc_pages_nodemask+0xdc0/0xdf0
 [<0000000000000000>] zs_malloc+0x148/0x3d0
 [<0000000000000000>] zram_bvec_rw+0x410/0x798
 [<0000000000000000>] zram_rw_page+0x88/0xdc
 [<0000000000000000>] bdev_write_page+0x70/0xbc
 [<0000000000000000>] __swap_writepage+0x58/0x37c
 [<0000000000000000>] swap_writepage+0x40/0x4c
 [<0000000000000000>] shrink_page_list+0xc30/0xf48
 [<0000000000000000>] shrink_inactive_list+0x2b0/0x61c
 [<0000000000000000>] shrink_node_memcg+0x23c/0x618
 [<0000000000000000>] shrink_node+0x1c8/0x304
 [<0000000000000000>] kswapd+0x680/0x7c4
 [<0000000000000000>] kthread+0x110/0x120
 [<0000000000000000>] ret_from_fork+0x10/0x18
 Mem-Info:
 active_anon:111826 inactive_anon:65557 isolated_anon:0\x0a active_file:44260 inactive_file:83422 isolated_file:0\x0a unevictable:4158 dirty:117 writeback:0 unstable:0\x0a            slab_reclaimable:13943 slab_unreclaimable:43315\x0a mapped:102511 shmem:3299 pagetables:19566 bounce:0\x0a free:3510 free_pcp:553 free_cma:0
 Node 0 active_anon:447304kB inactive_anon:262228kB active_file:177040kB inactive_file:333688kB unevictable:16632kB isolated(anon):0kB isolated(file):0kB mapped:410044kB d irty:468kB writeback:0kB shmem:13196kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
 Normal free:14040kB min:7440kB low:94500kB high:98136kB reserved_highatomic:32768KB active_anon:447336kB inactive_anon:261668kB active_file:177572kB inactive_file:333768k           B unevictable:16632kB writepending:480kB present:4081664kB managed:3637088kB mlocked:16632kB kernel_stack:47072kB pagetables:78264kB bounce:0kB free_pcp:2280kB local_pcp:720kB free_cma:0kB        [ 4738.329607] lowmem_reserve[]: 0 0
 Normal: 860*4kB (H) 453*8kB (H) 180*16kB (H) 26*32kB (H) 34*64kB (H) 6*128kB (H) 2*256kB (H) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 14232kB

This is trace log which shows GFP_HIGHUSER consumes free pages right
before ALLOC_NO_WATERMARKS.

  <...>-22275 [006] ....   889.213383: mm_page_alloc: page=00000000d2be5665 pfn=970744 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213385: mm_page_alloc: page=000000004b2335c2 pfn=970745 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213387: mm_page_alloc: page=00000000017272e1 pfn=970278 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213389: mm_page_alloc: page=00000000c4be79fb pfn=970279 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213391: mm_page_alloc: page=00000000f8a51d4f pfn=970260 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213393: mm_page_alloc: page=000000006ba8f5ac pfn=970261 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213395: mm_page_alloc: page=00000000819f1cd3 pfn=970196 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
  <...>-22275 [006] ....   889.213396: mm_page_alloc: page=00000000f6b72a64 pfn=970197 order=0 migratetype=0 nr_free=3650 gfp_flags=GFP_HIGHUSER|__GFP_ZERO
kswapd0-1207  [005] ...1   889.213398: mm_page_alloc: page= (null) pfn=0 order=0 migratetype=1 nr_free=3650 gfp_flags=GFP_NOWAIT|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_MOVABLE

[jaewon31.kim@samsung.com: remove redundant code for high-order]
  Link: http://lkml.kernel.org/r/20200623035242.27232-1-jaewon31.kim@samsung.com

Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20200619235958.11283-1-jaewon31.kim@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/page_alloc.c | 65 ++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9c35403..237463d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3130,6 +3130,29 @@ static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
 
 #endif /* CONFIG_FAIL_PAGE_ALLOC */
 
+static inline long __zone_watermark_unusable_free(struct zone *z,
+				unsigned int order, unsigned int alloc_flags)
+{
+	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
+	long unusable_free = (1 << order) - 1;
+
+	/*
+	 * If the caller does not have rights to ALLOC_HARDER then subtract
+	 * the high-atomic reserves. This will over-estimate the size of the
+	 * atomic reserve but it avoids a search.
+	 */
+	if (likely(!alloc_harder))
+		unusable_free += z->nr_reserved_highatomic;
+
+#ifdef CONFIG_CMA
+	/* If allocation can't use CMA areas don't use free CMA pages */
+	if (!(alloc_flags & ALLOC_CMA))
+		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
+
+	return unusable_free;
+}
+
 /*
  * Return true if free base pages are above 'mark'. For high-order checks it
  * will return true of the order-0 watermark is reached and there is at least
@@ -3145,19 +3168,12 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
 
 	/* free_pages may go negative - that's OK */
-	free_pages -= (1 << order) - 1;
+	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
 
 	if (alloc_flags & ALLOC_HIGH)
 		min -= min / 2;
 
-	/*
-	 * If the caller does not have rights to ALLOC_HARDER then subtract
-	 * the high-atomic reserves. This will over-estimate the size of the
-	 * atomic reserve but it avoids a search.
-	 */
-	if (likely(!alloc_harder)) {
-		free_pages -= z->nr_reserved_highatomic;
-	} else {
+	if (unlikely(alloc_harder)) {
 		/*
 		 * OOM victims can try even harder than normal ALLOC_HARDER
 		 * users on the grounds that it's definitely going to be in
@@ -3170,13 +3186,6 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 			min -= min / 4;
 	}
 
-
-#ifdef CONFIG_CMA
-	/* If allocation can't use CMA areas don't use free CMA pages */
-	if (!(alloc_flags & ALLOC_CMA))
-		free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
-#endif
-
 	/*
 	 * Check watermarks for an order-0 allocation request. If these
 	 * are not met, then a high-order request also cannot go ahead
@@ -3225,24 +3234,22 @@ bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
 		unsigned long mark, int classzone_idx, unsigned int alloc_flags)
 {
-	long free_pages = zone_page_state(z, NR_FREE_PAGES);
-	long cma_pages = 0;
+	long free_pages;
 
-#ifdef CONFIG_CMA
-	/* If allocation can't use CMA areas don't use free CMA pages */
-	if (!(alloc_flags & ALLOC_CMA))
-		cma_pages = zone_page_state(z, NR_FREE_CMA_PAGES);
-#endif
+	free_pages = zone_page_state(z, NR_FREE_PAGES);
 
 	/*
 	 * Fast check for order-0 only. If this fails then the reserves
-	 * need to be calculated. There is a corner case where the check
-	 * passes but only the high-order atomic reserve are free. If
-	 * the caller is !atomic then it'll uselessly search the free
-	 * list. That corner case is then slower but it is harmless.
+	 * need to be calculated.
 	 */
-	if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserve[classzone_idx])
-		return true;
+	if (!order) {
+		long fast_free;
+
+		fast_free = free_pages;
+		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
+		if (fast_free > mark + z->lowmem_reserve[classzone_idx])
+			return true;
+	}
 
 	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
 					free_pages);
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 24+ messages in thread

* [PATCH v2 stable-4.19 3/3] page_alloc: fix invalid watermark check on a negative value
  2022-09-25 10:35           ` [PATCH v2 " wangyong
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
@ 2022-09-25 10:35             ` wangyong
  2022-10-02 15:37             ` [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
  3 siblings, 0 replies; 24+ messages in thread
From: wangyong @ 2022-09-25 10:35 UTC (permalink / raw)
  To: gregkh
  Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12,
	yongw.pur, Minchan Kim, Baoquan He, Vlastimil Babka,
	Johannes Weiner, Yong-Taek Lee, stable, Andrew Morton

From: Jaewon Kim <jaewon31.kim@samsung.com>

[ backport of commit 9282012fc0aa248b77a69f5eb802b67c5a16bb13 ]

There was a report that a task is waiting at the
throttle_direct_reclaim. The pgscan_direct_throttle in vmstat was
increasing.

This is a bug where zone_watermark_fast returns true even when the free
is very low. The commit f27ce0e14088 ("page_alloc: consider highatomic
reserve in watermark fast") changed the watermark fast to consider
highatomic reserve. But it did not handle a negative value case which
can be happened when reserved_highatomic pageblock is bigger than the
actual free.

If watermark is considered as ok for the negative value, allocating
contexts for order-0 will consume all free pages without direct reclaim,
and finally free page may become depleted except highatomic free.

Then allocating contexts may fall into throttle_direct_reclaim. This
symptom may easily happen in a system where wmark min is low and other
reclaimers like kswapd does not make free pages quickly.

Handle the negative case by using MIN.

Link: https://lkml.kernel.org/r/20220725095212.25388-1-jaewon31.kim@samsung.com
Fixes: f27ce0e14088 ("page_alloc: consider highatomic reserve in watermark fast")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: GyeongHwan Hong <gh21.hong@samsung.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kerenl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_alloc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 237463d..d6d8a37 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3243,11 +3243,15 @@ static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
 	 * need to be calculated.
 	 */
 	if (!order) {
-		long fast_free;
+		long usable_free;
+		long reserved;
 
-		fast_free = free_pages;
-		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
-		if (fast_free > mark + z->lowmem_reserve[classzone_idx])
+		usable_free = free_pages;
+		reserved = __zone_watermark_unusable_free(z, 0, alloc_flags);
+
+		/* reserved may over estimate high-atomic reserves. */
+		usable_free -= min(usable_free, reserved);
+		if (usable_free > mark + z->lowmem_reserve[classzone_idx])
 			return true;
 	}
 
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-09-25 10:35           ` [PATCH v2 " wangyong
                               ` (2 preceding siblings ...)
  2022-09-25 10:35             ` [PATCH v2 stable-4.19 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
@ 2022-10-02 15:37             ` Greg KH
       [not found]               ` <CAOH5QeB2EqpqQd6fw-P199w8K8-3QNv_t-u_Wn1BLnfaSscmCg@mail.gmail.com>
  3 siblings, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-10-02 15:37 UTC (permalink / raw)
  To: wangyong; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12

On Sun, Sep 25, 2022 at 03:35:26AM -0700, wangyong wrote:
> Here are the corresponding backports to 4.19.
> And fix classzone_idx context differences causing patch merge conflicts.
> 
> Original commit IDS:
> 	3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
> 	f27ce0e page_alloc: consider highatomic reserve in watermark fast
> 	9282012 page_alloc: fix invalid watermark check on a negative value
> 
> Changes from v1:
> - Add commit information of the original patches.

None of these have your signed-off-by on them showing that the backport
came from you and that you are responsible for them.

So even if we did think they were valid to backport, I can't take them
as-is :(

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

[parent not found: <CAOH5QeB2EqpqQd6fw-P199w8K8-3QNv_t-u_Wn1BLnfaSscmCg@mail.gmail.com>]

* Re: [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
       [not found]               ` <CAOH5QeB2EqpqQd6fw-P199w8K8-3QNv_t-u_Wn1BLnfaSscmCg@mail.gmail.com>
@ 2022-10-07 16:41                 ` Greg KH
  2022-10-10 15:47                   ` yong w
  0 siblings, 1 reply; 24+ messages in thread
From: Greg KH @ 2022-10-07 16:41 UTC (permalink / raw)
  To: yong w; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12

A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Fri, Oct 07, 2022 at 04:53:50PM +0800, yong w wrote:
> Is it ok to add my signed-off-by? my signed-off-by is as follows:
> 
>   Signed-off-by: wangyong <wang.yong12@zte.com.cn>

For obvious reasons, I can not take that from a random gmail account
(nor should ZTE want me to do that.)

Please fix up your email systems and do this properly and send the
series again.

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-10-07 16:41                 ` Greg KH
@ 2022-10-10 15:47                   ` yong w
  2022-10-10 15:58                     ` Greg KH
  0 siblings, 1 reply; 24+ messages in thread
From: yong w @ 2022-10-10 15:47 UTC (permalink / raw)
  To: Greg KH; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12

Greg KH <gregkh@linuxfoundation.org> 于2022年10月8日周六 00:40写道：
>
> A: http://en.wikipedia.org/wiki/Top_post
> Q: Were do I find info about this thing called top-posting?
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing in e-mail?
>
> A: No.
> Q: Should I include quotations after my reply?
>
> http://daringfireball.net/2007/07/on_top
>
>
> On Fri, Oct 07, 2022 at 04:53:50PM +0800, yong w wrote:
> > Is it ok to add my signed-off-by? my signed-off-by is as follows:
> >
> >   Signed-off-by: wangyong <wang.yong12@zte.com.cn>
>
> For obvious reasons, I can not take that from a random gmail account
> (nor should ZTE want me to do that.)
>
> Please fix up your email systems and do this properly and send the
> series again.
>
> thanks,
>
> greg k-h

Sorry, our mail system cannot send external mail for some reason.
And this is my email, I can receive an email and reply to it.

thanks.

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19
  2022-10-10 15:47                   ` yong w
@ 2022-10-10 15:58                     ` Greg KH
  0 siblings, 0 replies; 24+ messages in thread
From: Greg KH @ 2022-10-10 15:58 UTC (permalink / raw)
  To: yong w; +Cc: jaewon31.kim, linux-kernel, mhocko, stable, wang.yong12

On Mon, Oct 10, 2022 at 11:47:30PM +0800, yong w wrote:
> Greg KH <gregkh@linuxfoundation.org> 于2022年10月8日周六 00:40写道：
> >
> > A: http://en.wikipedia.org/wiki/Top_post
> > Q: Were do I find info about this thing called top-posting?
> > A: Because it messes up the order in which people normally read text.
> > Q: Why is top-posting such a bad thing?
> > A: Top-posting.
> > Q: What is the most annoying thing in e-mail?
> >
> > A: No.
> > Q: Should I include quotations after my reply?
> >
> > http://daringfireball.net/2007/07/on_top
> >
> >
> > On Fri, Oct 07, 2022 at 04:53:50PM +0800, yong w wrote:
> > > Is it ok to add my signed-off-by? my signed-off-by is as follows:
> > >
> > >   Signed-off-by: wangyong <wang.yong12@zte.com.cn>
> >
> > For obvious reasons, I can not take that from a random gmail account
> > (nor should ZTE want me to do that.)
> >
> > Please fix up your email systems and do this properly and send the
> > series again.
> >
> > thanks,
> >
> > greg k-h
> 
> Sorry, our mail system cannot send external mail for some reason.

Sorry, then I can not attribute anything to your company.  It has
already been warned that it can not continue to contribute to the Linux
kernel and some of your gmail "aliases" have been banned from the
mailing lists.

Please fix your email system so that you can properly contribute to
Linux.

> And this is my email, I can receive an email and reply to it.

Yes, but I have no proof that your ZTE email is correct, only that this
is a random gmail.com address :(

What would you do if you were in my situation?

Please work with your IT group to fix their email systems.

good luck,

greg k-h

^ permalink raw reply	[flat|nested] 24+ messages in thread

[parent not found: <CGME20220916094017epcas1p1deed4041f897d2bf0e0486554d79b3af@epcms1p4>]

* RE: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
       [not found]     ` <CGME20220916094017epcas1p1deed4041f897d2bf0e0486554d79b3af@epcms1p4>
@ 2022-09-18  1:41       ` Jaewon Kim
  2022-09-19 13:21         ` yong w
  0 siblings, 1 reply; 24+ messages in thread
From: Jaewon Kim @ 2022-09-18  1:41 UTC (permalink / raw)
  To: Greg KH, yong w
  Cc: Jaewon Kim, mhocko, linux-kernel, stable, wang.yong12, YongTaek Lee

>On Wed, Sep 14, 2022 at 08:46:15AM +0800, yong w wrote:
>> Greg KH <gregkh@linuxfoundation.org> 于2022年9月13日周二 21:54?道：
>> 
>> >
>> > On Tue, Sep 13, 2022 at 09:09:47PM +0800, yong wrote:
>> > > Hello,
>> > > This patch is required to be patched in linux-5.4.y and linux-4.19.y.
>> >
>> > What is "this patch"?  There is no context here :(
>> >
>> Sorry, I forgot to quote the original patch. the patch is as follows
>> 
>>     f27ce0e page_alloc: consider highatomic reserve in watermark fast
>> 
>> > > In addition to that, the following two patches are somewhat related:
>> > >
>> > >       3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
>> > >       9282012 page_alloc: fix invalid watermark check on a negative value
>> >
>> > In what way?  What should be done here by us?
>> >
>> 
>> I think these two patches should also be merged.
>> 
>>     The classzone_idx  parameter is used in the zone_watermark_fast
>> functionzone, and 3334a45 use ac->high_zoneidx for classzone_idx.
>>     "9282012 page_alloc: fix invalid watermark check on a negative
>> value"  fix f27ce0e introduced issues
>
>Ok, I need an ack by all the developers involved in those commits, as
>well as the subsystem maintainer so that I know it's ok to take them.
>
>Can you provide a series of backported and tested patches so that they
>are easy to review?
>
>thanks,
>
>greg k-h

Hello I didn't know my Act is needed to merge it.

Acked-by: Jaewon Kim <jaewon31.kim@samsung.com>

I don't understand well why the commit f27ce0e has dependency on 3334a45, though.

Thank you
Jaewon Kim

^ permalink raw reply	[flat|nested] 24+ messages in thread

* Re: [PATCH v4] page_alloc: consider highatomic reserve in watermark fast
  2022-09-18  1:41       ` [PATCH v4] page_alloc: consider highatomic reserve in watermark fast Jaewon Kim
@ 2022-09-19 13:21         ` yong w
  0 siblings, 0 replies; 24+ messages in thread
From: yong w @ 2022-09-19 13:21 UTC (permalink / raw)
  To: jaewon31.kim
  Cc: Greg KH, mhocko, linux-kernel, stable, wang.yong12, YongTaek Lee

Jaewon Kim <jaewon31.kim@samsung.com> 于2022年9月19日周一 09:08写道：
>
> >On Wed, Sep 14, 2022 at 08:46:15AM +0800, yong w wrote:
> >> Greg KH <gregkh@linuxfoundation.org> 于2022年9月13日周二 21:54?道：
> >>
> >> >
> >> > On Tue, Sep 13, 2022 at 09:09:47PM +0800, yong wrote:
> >> > > Hello,
> >> > > This patch is required to be patched in linux-5.4.y and linux-4.19.y.
> >> >
> >> > What is "this patch"?  There is no context here :(
> >> >
> >> Sorry, I forgot to quote the original patch. the patch is as follows
> >>
> >>     f27ce0e page_alloc: consider highatomic reserve in watermark fast
> >>
> >> > > In addition to that, the following two patches are somewhat related:
> >> > >
> >> > >       3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
> >> > >       9282012 page_alloc: fix invalid watermark check on a negative value
> >> >
> >> > In what way?  What should be done here by us?
> >> >
> >>
> >> I think these two patches should also be merged.
> >>
> >>     The classzone_idx  parameter is used in the zone_watermark_fast
> >> functionzone, and 3334a45 use ac->high_zoneidx for classzone_idx.
> >>     "9282012 page_alloc: fix invalid watermark check on a negative
> >> value"  fix f27ce0e introduced issues
> >
> >Ok, I need an ack by all the developers involved in those commits, as
> >well as the subsystem maintainer so that I know it's ok to take them.
> >
> >Can you provide a series of backported and tested patches so that they
> >are easy to review?
> >
> >thanks,
> >
> >greg k-h
>
> Hello I didn't know my Act is needed to merge it.
>
> Acked-by: Jaewon Kim <jaewon31.kim@samsung.com>
>
> I don't understand well why the commit f27ce0e has dependency on 3334a45, though.
>
Hello, the classzone_idx is used in the zone_watermark_fast function, and
there will be conflicts when f27ce0e is merged.

Looking back, the following two patches adjust the classzone_idx parameter.
     3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx
     97a225e mm/page_alloc: integrate classzone_idx and high_zoneidx
and 3334a45 is the key modification.

Actually, I think 3334a45 can be merged or not.

Thanks.

^ permalink raw reply	[flat|nested] 24+ messages in thread

end of thread, other threads:[~2022-10-10 15:58 UTC | newest]

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-13 13:09 [PATCH v4] page_alloc: consider highatomic reserve in watermark fast yong
2022-09-13 13:54 ` Greg KH
2022-09-14  0:46   ` yong w
2022-09-16  9:40     ` Greg KH
2022-09-16 17:05       ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 wangyong
2022-09-16 17:05         ` [PATCH 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
2022-09-16 17:09           ` kernel test robot
2022-09-16 17:05         ` [PATCH 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
2022-09-16 17:05         ` [PATCH 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
2022-09-20 17:41         ` [PATCH stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
2022-09-25 10:35           ` [PATCH v2 " wangyong
2022-09-25 10:35             ` [PATCH v2 stable-4.19 1/3] mm/page_alloc: use ac->high_zoneidx for classzone_idx wangyong
2022-09-25 10:36               ` kernel test robot
2022-09-25 11:00               ` Greg KH
2022-09-25 14:32                 ` yong w
2022-09-26  6:46                   ` Greg KH
2022-09-25 10:35             ` [PATCH v2 stable-4.19 2/3] page_alloc: consider highatomic reserve in watermark fast wangyong
2022-09-25 10:35             ` [PATCH v2 stable-4.19 3/3] page_alloc: fix invalid watermark check on a negative value wangyong
2022-10-02 15:37             ` [PATCH v2 stable-4.19 0/3] page_alloc: consider highatomic reserve in watermark fast backports to 4.19 Greg KH
     [not found]               ` <CAOH5QeB2EqpqQd6fw-P199w8K8-3QNv_t-u_Wn1BLnfaSscmCg@mail.gmail.com>
2022-10-07 16:41                 ` Greg KH
2022-10-10 15:47                   ` yong w
2022-10-10 15:58                     ` Greg KH
     [not found]     ` <CGME20220916094017epcas1p1deed4041f897d2bf0e0486554d79b3af@epcms1p4>
2022-09-18  1:41       ` [PATCH v4] page_alloc: consider highatomic reserve in watermark fast Jaewon Kim
2022-09-19 13:21         ` yong w

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