* [PATCH 0/2] fix a kernel oops in reading sysfs valid_zones
@ 2017-01-26 21:44 ` Toshi Kani
0 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel
A sysfs memory file is created for each 128MiB or 2GiB of a memory
block on x86. [1] When the start address of a memory block is not
backed by struct page, i.e. memory range is not aligned by the memory
block size, reading its valid_zones attribute file leads to a kernel
oops. This patch-set fixes this issue.
Patch 1 first fixes an issue in test_pages_in_a_zone() that it does
not test the start section.
Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone()
to return valid [start, end).
[1] 2GB when the system has 64GB or larger memory.
---
Toshi Kani (2):
1/2 mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
2/2 base/memory, hotplug: fix a kernel oops in show_valid_zones()
---
drivers/base/memory.c | 12 ++++++------
include/linux/memory_hotplug.h | 3 ++-
mm/memory_hotplug.c | 28 +++++++++++++++++++++-------
3 files changed, 29 insertions(+), 14 deletions(-)
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 0/2] fix a kernel oops in reading sysfs valid_zones
@ 2017-01-26 21:44 ` Toshi Kani
0 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel
A sysfs memory file is created for each 128MiB or 2GiB of a memory
block on x86. [1] When the start address of a memory block is not
backed by struct page, i.e. memory range is not aligned by the memory
block size, reading its valid_zones attribute file leads to a kernel
oops. This patch-set fixes this issue.
Patch 1 first fixes an issue in test_pages_in_a_zone() that it does
not test the start section.
Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone()
to return valid [start, end).
[1] 2GB when the system has 64GB or larger memory.
---
Toshi Kani (2):
1/2 mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
2/2 base/memory, hotplug: fix a kernel oops in show_valid_zones()
---
drivers/base/memory.c | 12 ++++++------
include/linux/memory_hotplug.h | 3 ++-
mm/memory_hotplug.c | 28 +++++++++++++++++++++-------
3 files changed, 29 insertions(+), 14 deletions(-)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
2017-01-26 21:44 ` Toshi Kani
@ 2017-01-26 21:44 ` Toshi Kani
-1 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel, Toshi Kani
test_pages_in_a_zone() does not check 'start_pfn' when it is
aligned by section since 'sec_end_pfn' is set equal to 'pfn'.
Since this function is called for testing the range of a sysfs
memory file, 'start_pfn' is always aligned by section.
Fix it by properly setting 'sec_end_pfn' to the next section pfn.
Also make sure that this function returns 1 only when the range
belongs to a zone.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
---
mm/memory_hotplug.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e43142c1..7836606 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1477,7 +1477,7 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
}
/*
- * Confirm all pages in a range [start, end) is belongs to the same zone.
+ * Confirm all pages in a range [start, end) belong to the same zone.
*/
int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
{
@@ -1485,9 +1485,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
struct zone *zone = NULL;
struct page *page;
int i;
- for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
+ for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
pfn < end_pfn;
- pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
+ pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
/* Make sure the memory section is present first */
if (!present_section_nr(pfn_to_section_nr(pfn)))
continue;
@@ -1506,7 +1506,11 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
zone = page_zone(page);
}
}
- return 1;
+
+ if (zone)
+ return 1;
+ else
+ return 0;
}
/*
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 1/2] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
@ 2017-01-26 21:44 ` Toshi Kani
0 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel, Toshi Kani
test_pages_in_a_zone() does not check 'start_pfn' when it is
aligned by section since 'sec_end_pfn' is set equal to 'pfn'.
Since this function is called for testing the range of a sysfs
memory file, 'start_pfn' is always aligned by section.
Fix it by properly setting 'sec_end_pfn' to the next section pfn.
Also make sure that this function returns 1 only when the range
belongs to a zone.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
---
mm/memory_hotplug.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e43142c1..7836606 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1477,7 +1477,7 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
}
/*
- * Confirm all pages in a range [start, end) is belongs to the same zone.
+ * Confirm all pages in a range [start, end) belong to the same zone.
*/
int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
{
@@ -1485,9 +1485,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
struct zone *zone = NULL;
struct page *page;
int i;
- for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
+ for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
pfn < end_pfn;
- pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
+ pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
/* Make sure the memory section is present first */
if (!present_section_nr(pfn_to_section_nr(pfn)))
continue;
@@ -1506,7 +1506,11 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
zone = page_zone(page);
}
}
- return 1;
+
+ if (zone)
+ return 1;
+ else
+ return 0;
}
/*
--
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-01-26 21:44 ` Toshi Kani
@ 2017-01-26 21:44 ` Toshi Kani
-1 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel, Toshi Kani
Reading a sysfs memoryN/valid_zones file leads to the following
oops when the first page of a range is not backed by struct page.
show_valid_zones() assumes that 'start_pfn' is always valid for
page_zone().
BUG: unable to handle kernel paging request at ffffea017a000000
IP: show_valid_zones+0x6f/0x160
Since test_pages_in_a_zone() already checks holes, extend this
function to return 'valid_start' and 'valid_end' for a given range.
show_valid_zones() then proceeds with the valid range.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
---
drivers/base/memory.c | 12 ++++++------
include/linux/memory_hotplug.h | 3 ++-
mm/memory_hotplug.c | 20 +++++++++++++++-----
3 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 8ab8ea1..2c9aad9 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -389,33 +389,33 @@ static ssize_t show_valid_zones(struct device *dev,
{
struct memory_block *mem = to_memory_block(dev);
unsigned long start_pfn, end_pfn;
+ unsigned long valid_start, valid_end, valid_pages;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
- struct page *first_page;
struct zone *zone;
int zone_shift = 0;
start_pfn = section_nr_to_pfn(mem->start_section_nr);
end_pfn = start_pfn + nr_pages;
- first_page = pfn_to_page(start_pfn);
/* The block contains more than one zone can not be offlined. */
- if (!test_pages_in_a_zone(start_pfn, end_pfn))
+ if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
return sprintf(buf, "none\n");
- zone = page_zone(first_page);
+ zone = page_zone(pfn_to_page(valid_start));
+ valid_pages = valid_end - valid_start;
/* MMOP_ONLINE_KEEP */
sprintf(buf, "%s", zone->name);
/* MMOP_ONLINE_KERNEL */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_NORMAL);
+ zone_shift = zone_can_shift(valid_start, valid_pages, ZONE_NORMAL);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
}
/* MMOP_ONLINE_MOVABLE */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_MOVABLE);
+ zone_shift = zone_can_shift(valid_start, valid_pages, ZONE_MOVABLE);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 01033fa..b6aa972 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -85,7 +85,8 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
/* VM interface that may be used by firmware interface */
extern int online_pages(unsigned long, unsigned long, int);
-extern int test_pages_in_a_zone(unsigned long, unsigned long);
+extern int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+ unsigned long *valid_start, unsigned long *valid_end);
extern void __offline_isolated_pages(unsigned long, unsigned long);
typedef void (*online_page_callback_t)(struct page *page);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 7836606..9de2f83 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1478,10 +1478,13 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
/*
* Confirm all pages in a range [start, end) belong to the same zone.
+ * When true, return its valid [start, end).
*/
-int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+ unsigned long *valid_start, unsigned long *valid_end)
{
unsigned long pfn, sec_end_pfn;
+ unsigned long start, end;
struct zone *zone = NULL;
struct page *page;
int i;
@@ -1503,14 +1506,20 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
page = pfn_to_page(pfn + i);
if (zone && page_zone(page) != zone)
return 0;
+ if (!zone)
+ start = pfn + i;
zone = page_zone(page);
+ end = pfn + MAX_ORDER_NR_PAGES;
}
}
- if (zone)
+ if (zone) {
+ *valid_start = start;
+ *valid_end = end;
return 1;
- else
+ } else {
return 0;
+ }
}
/*
@@ -1837,6 +1846,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
long offlined_pages;
int ret, drain, retry_max, node;
unsigned long flags;
+ unsigned long valid_start, valid_end;
struct zone *zone;
struct memory_notify arg;
@@ -1847,10 +1857,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
return -EINVAL;
/* This makes hotplug much easier...and readable.
we assume this for now. .*/
- if (!test_pages_in_a_zone(start_pfn, end_pfn))
+ if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
return -EINVAL;
- zone = page_zone(pfn_to_page(start_pfn));
+ zone = page_zone(pfn_to_page(valid_start));
node = zone_to_nid(zone);
nr_pages = end_pfn - start_pfn;
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
@ 2017-01-26 21:44 ` Toshi Kani
0 siblings, 0 replies; 12+ messages in thread
From: Toshi Kani @ 2017-01-26 21:44 UTC (permalink / raw)
To: akpm, gregkh
Cc: linux-mm, zhenzhang.zhang, arbab, dan.j.williams, abanman,
rientjes, linux-kernel, Toshi Kani
Reading a sysfs memoryN/valid_zones file leads to the following
oops when the first page of a range is not backed by struct page.
show_valid_zones() assumes that 'start_pfn' is always valid for
page_zone().
BUG: unable to handle kernel paging request at ffffea017a000000
IP: show_valid_zones+0x6f/0x160
Since test_pages_in_a_zone() already checks holes, extend this
function to return 'valid_start' and 'valid_end' for a given range.
show_valid_zones() then proceeds with the valid range.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
---
drivers/base/memory.c | 12 ++++++------
include/linux/memory_hotplug.h | 3 ++-
mm/memory_hotplug.c | 20 +++++++++++++++-----
3 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 8ab8ea1..2c9aad9 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -389,33 +389,33 @@ static ssize_t show_valid_zones(struct device *dev,
{
struct memory_block *mem = to_memory_block(dev);
unsigned long start_pfn, end_pfn;
+ unsigned long valid_start, valid_end, valid_pages;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
- struct page *first_page;
struct zone *zone;
int zone_shift = 0;
start_pfn = section_nr_to_pfn(mem->start_section_nr);
end_pfn = start_pfn + nr_pages;
- first_page = pfn_to_page(start_pfn);
/* The block contains more than one zone can not be offlined. */
- if (!test_pages_in_a_zone(start_pfn, end_pfn))
+ if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
return sprintf(buf, "none\n");
- zone = page_zone(first_page);
+ zone = page_zone(pfn_to_page(valid_start));
+ valid_pages = valid_end - valid_start;
/* MMOP_ONLINE_KEEP */
sprintf(buf, "%s", zone->name);
/* MMOP_ONLINE_KERNEL */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_NORMAL);
+ zone_shift = zone_can_shift(valid_start, valid_pages, ZONE_NORMAL);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
}
/* MMOP_ONLINE_MOVABLE */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_MOVABLE);
+ zone_shift = zone_can_shift(valid_start, valid_pages, ZONE_MOVABLE);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 01033fa..b6aa972 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -85,7 +85,8 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
/* VM interface that may be used by firmware interface */
extern int online_pages(unsigned long, unsigned long, int);
-extern int test_pages_in_a_zone(unsigned long, unsigned long);
+extern int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+ unsigned long *valid_start, unsigned long *valid_end);
extern void __offline_isolated_pages(unsigned long, unsigned long);
typedef void (*online_page_callback_t)(struct page *page);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 7836606..9de2f83 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1478,10 +1478,13 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
/*
* Confirm all pages in a range [start, end) belong to the same zone.
+ * When true, return its valid [start, end).
*/
-int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+ unsigned long *valid_start, unsigned long *valid_end)
{
unsigned long pfn, sec_end_pfn;
+ unsigned long start, end;
struct zone *zone = NULL;
struct page *page;
int i;
@@ -1503,14 +1506,20 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
page = pfn_to_page(pfn + i);
if (zone && page_zone(page) != zone)
return 0;
+ if (!zone)
+ start = pfn + i;
zone = page_zone(page);
+ end = pfn + MAX_ORDER_NR_PAGES;
}
}
- if (zone)
+ if (zone) {
+ *valid_start = start;
+ *valid_end = end;
return 1;
- else
+ } else {
return 0;
+ }
}
/*
@@ -1837,6 +1846,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
long offlined_pages;
int ret, drain, retry_max, node;
unsigned long flags;
+ unsigned long valid_start, valid_end;
struct zone *zone;
struct memory_notify arg;
@@ -1847,10 +1857,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
return -EINVAL;
/* This makes hotplug much easier...and readable.
we assume this for now. .*/
- if (!test_pages_in_a_zone(start_pfn, end_pfn))
+ if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
return -EINVAL;
- zone = page_zone(pfn_to_page(start_pfn));
+ zone = page_zone(pfn_to_page(valid_start));
node = zone_to_nid(zone);
nr_pages = end_pfn - start_pfn;
--
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/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-01-26 21:44 ` Toshi Kani
@ 2017-01-26 21:52 ` Andrew Morton
-1 siblings, 0 replies; 12+ messages in thread
From: Andrew Morton @ 2017-01-26 21:52 UTC (permalink / raw)
To: Toshi Kani
Cc: gregkh, linux-mm, zhenzhang.zhang, arbab, dan.j.williams,
abanman, rientjes, linux-kernel
On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com> wrote:
> Reading a sysfs memoryN/valid_zones file leads to the following
> oops when the first page of a range is not backed by struct page.
> show_valid_zones() assumes that 'start_pfn' is always valid for
> page_zone().
>
> BUG: unable to handle kernel paging request at ffffea017a000000
> IP: show_valid_zones+0x6f/0x160
>
> Since test_pages_in_a_zone() already checks holes, extend this
> function to return 'valid_start' and 'valid_end' for a given range.
> show_valid_zones() then proceeds with the valid range.
This doesn't apply to current mainline due to changes in
zone_can_shift(). Please redo and resend.
Please also update the changelog to provide sufficient information for
others to decide which kernel(s) need the fix. In particular: under
what circumstances will it occur? On real machines which real people
own?
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
@ 2017-01-26 21:52 ` Andrew Morton
0 siblings, 0 replies; 12+ messages in thread
From: Andrew Morton @ 2017-01-26 21:52 UTC (permalink / raw)
To: Toshi Kani
Cc: gregkh, linux-mm, zhenzhang.zhang, arbab, dan.j.williams,
abanman, rientjes, linux-kernel
On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com> wrote:
> Reading a sysfs memoryN/valid_zones file leads to the following
> oops when the first page of a range is not backed by struct page.
> show_valid_zones() assumes that 'start_pfn' is always valid for
> page_zone().
>
> BUG: unable to handle kernel paging request at ffffea017a000000
> IP: show_valid_zones+0x6f/0x160
>
> Since test_pages_in_a_zone() already checks holes, extend this
> function to return 'valid_start' and 'valid_end' for a given range.
> show_valid_zones() then proceeds with the valid range.
This doesn't apply to current mainline due to changes in
zone_can_shift(). Please redo and resend.
Please also update the changelog to provide sufficient information for
others to decide which kernel(s) need the fix. In particular: under
what circumstances will it occur? On real machines which real people
own?
--
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-01-26 21:52 ` Andrew Morton
(?)
@ 2017-01-26 22:26 ` Kani, Toshimitsu
2017-01-27 7:48 ` gregkh
-1 siblings, 1 reply; 12+ messages in thread
From: Kani, Toshimitsu @ 2017-01-26 22:26 UTC (permalink / raw)
To: akpm
Cc: zhenzhang.zhang, linux-kernel, arbab, abanman, linux-mm,
dan.j.williams, gregkh, rientjes
On Thu, 2017-01-26 at 13:52 -0800, Andrew Morton wrote:
> On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com>
> wrote:
>
> > Reading a sysfs memoryN/valid_zones file leads to the following
> > oops when the first page of a range is not backed by struct page.
> > show_valid_zones() assumes that 'start_pfn' is always valid for
> > page_zone().
> >
> > BUG: unable to handle kernel paging request at ffffea017a000000
> > IP: show_valid_zones+0x6f/0x160
> >
> > Since test_pages_in_a_zone() already checks holes, extend this
> > function to return 'valid_start' and 'valid_end' for a given range.
> > show_valid_zones() then proceeds with the valid range.
>
> This doesn't apply to current mainline due to changes in
> zone_can_shift(). Please redo and resend.
Sorry, I will rebase to the -mm tree and resend the patches.
> Please also update the changelog to provide sufficient information
> for others to decide which kernel(s) need the fix. In particular:
> under what circumstances will it occur? On real machines which real
> people own?
Yes, this issue happens on real x86 machines with 64GiB or more memory.
On such systems, the memory block size is bumped up to 2GiB. [1]
Here is an example system. 0x3240000000 is only aligned by 1GiB and
its memory block starts from 0x3200000000, which is not backed by
struct page.
BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
I will add the descriptions to the patch.
[1] http://lkml.iu.edu/hypermail/linux/kernel/1411.0/02287.html
Thanks,
-Toshi
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-01-26 22:26 ` Kani, Toshimitsu
@ 2017-01-27 7:48 ` gregkh
0 siblings, 0 replies; 12+ messages in thread
From: gregkh @ 2017-01-27 7:48 UTC (permalink / raw)
To: Kani, Toshimitsu
Cc: akpm, zhenzhang.zhang, linux-kernel, arbab, abanman, linux-mm,
dan.j.williams, rientjes
On Thu, Jan 26, 2017 at 10:26:23PM +0000, Kani, Toshimitsu wrote:
> On Thu, 2017-01-26 at 13:52 -0800, Andrew Morton wrote:
> > On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com>
> > wrote:
> >
> > > Reading a sysfs memoryN/valid_zones file leads to the following
> > > oops when the first page of a range is not backed by struct page.
> > > show_valid_zones() assumes that 'start_pfn' is always valid for
> > > page_zone().
> > >
> > > BUG: unable to handle kernel paging request at ffffea017a000000
> > > IP: show_valid_zones+0x6f/0x160
> > >
> > > Since test_pages_in_a_zone() already checks holes, extend this
> > > function to return 'valid_start' and 'valid_end' for a given range.
> > > show_valid_zones() then proceeds with the valid range.
> >
> > This doesn't apply to current mainline due to changes in
> > zone_can_shift(). Please redo and resend.
>
> Sorry, I will rebase to the -mm tree and resend the patches.
>
> > Please also update the changelog to provide sufficient information
> > for others to decide which kernel(s) need the fix. In particular:
> > under what circumstances will it occur? On real machines which real
> > people own?
>
> Yes, this issue happens on real x86 machines with 64GiB or more memory.
> On such systems, the memory block size is bumped up to 2GiB. [1]
>
> Here is an example system. 0x3240000000 is only aligned by 1GiB and
> its memory block starts from 0x3200000000, which is not backed by
> struct page.
>
> BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
>
> I will add the descriptions to the patch.
Should it also be backported to the stable kernels to resolve the issue
there?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
@ 2017-01-27 7:48 ` gregkh
0 siblings, 0 replies; 12+ messages in thread
From: gregkh @ 2017-01-27 7:48 UTC (permalink / raw)
To: Kani, Toshimitsu
Cc: akpm, zhenzhang.zhang, linux-kernel, arbab, abanman, linux-mm,
dan.j.williams, rientjes
On Thu, Jan 26, 2017 at 10:26:23PM +0000, Kani, Toshimitsu wrote:
> On Thu, 2017-01-26 at 13:52 -0800, Andrew Morton wrote:
> > On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com>
> > wrote:
> >
> > > Reading a sysfs memoryN/valid_zones file leads to the following
> > > oops when the first page of a range is not backed by struct page.
> > > show_valid_zones() assumes that 'start_pfn' is always valid for
> > > page_zone().
> > >
> > > BUG: unable to handle kernel paging request at ffffea017a000000
> > > IP: show_valid_zones+0x6f/0x160
> > >
> > > Since test_pages_in_a_zone() already checks holes, extend this
> > > function to return 'valid_start' and 'valid_end' for a given range.
> > > show_valid_zones() then proceeds with the valid range.
> >
> > This doesn't apply to current mainline due to changes in
> > zone_can_shift(). Please redo and resend.
>
> Sorry, I will rebase to the -mm tree and resend the patches.
>
> > Please also update the changelog to provide sufficient information
> > for others to decide which kernel(s) need the fix. In particular:
> > under what circumstances will it occur? On real machines which real
> > people own?
>
> Yes, this issue happens on real x86 machines with 64GiB or more memory.
> On such systems, the memory block size is bumped up to 2GiB. [1]
>
> Here is an example system. 0x3240000000 is only aligned by 1GiB and
> its memory block starts from 0x3200000000, which is not backed by
> struct page.
>
> BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
>
> I will add the descriptions to the patch.
Should it also be backported to the stable kernels to resolve the issue
there?
thanks,
greg k-h
--
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 [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
2017-01-27 7:48 ` gregkh
(?)
@ 2017-01-27 17:47 ` Kani, Toshimitsu
-1 siblings, 0 replies; 12+ messages in thread
From: Kani, Toshimitsu @ 2017-01-27 17:47 UTC (permalink / raw)
To: gregkh
Cc: zhenzhang.zhang, linux-kernel, arbab, abanman, linux-mm,
dan.j.williams, akpm, rientjes
On Fri, 2017-01-27 at 08:48 +0100, gregkh@linuxfoundation.org wrote:
> On Thu, Jan 26, 2017 at 10:26:23PM +0000, Kani, Toshimitsu wrote:
> > On Thu, 2017-01-26 at 13:52 -0800, Andrew Morton wrote:
> > > On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com
> > > >
> > > wrote:
> > >
> > > > Reading a sysfs memoryN/valid_zones file leads to the following
> > > > oops when the first page of a range is not backed by struct
> > > > page. show_valid_zones() assumes that 'start_pfn' is always
> > > > valid for page_zone().
> > > >
> > > > BUG: unable to handle kernel paging request at
> > > > ffffea017a000000
> > > > IP: show_valid_zones+0x6f/0x160
> > > >
> > > > Since test_pages_in_a_zone() already checks holes, extend this
> > > > function to return 'valid_start' and 'valid_end' for a given
> > > > range. show_valid_zones() then proceeds with the valid range.
> > >
> > > This doesn't apply to current mainline due to changes in
> > > zone_can_shift(). Please redo and resend.
> >
> > Sorry, I will rebase to the -mm tree and resend the patches.
> >
> > > Please also update the changelog to provide sufficient
> > > information for others to decide which kernel(s) need the
> > > fix. In particular: under what circumstances will it occur? On
> > > real machines which real people own?
> >
> > Yes, this issue happens on real x86 machines with 64GiB or more
> > memory. On such systems, the memory block size is bumped up to
> > 2GiB. [1]
> >
> > Here is an example system. 0x3240000000 is only aligned by 1GiB
> > and its memory block starts from 0x3200000000, which is not backed
> > by struct page.
> >
> > BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
> >
> > I will add the descriptions to the patch.
>
> Should it also be backported to the stable kernels to resolve the
> issue there?
Yes, it should be backported to the stable kernels. The memory block
size change was made by commit bdee237c034, which was accepted to 3.9.
However, this patch-set depends on (and fixes) the change to
test_pages_in_a_zone() made by commit 5f0f2887f4, which was accepted to
4.4. So, in the current form, I'd recommend we backport it up to 4.4.
Thanks,
-Toshi
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2017-01-27 18:24 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-26 21:44 [PATCH 0/2] fix a kernel oops in reading sysfs valid_zones Toshi Kani
2017-01-26 21:44 ` Toshi Kani
2017-01-26 21:44 ` [PATCH 1/2] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone() Toshi Kani
2017-01-26 21:44 ` Toshi Kani
2017-01-26 21:44 ` [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones() Toshi Kani
2017-01-26 21:44 ` Toshi Kani
2017-01-26 21:52 ` Andrew Morton
2017-01-26 21:52 ` Andrew Morton
2017-01-26 22:26 ` Kani, Toshimitsu
2017-01-27 7:48 ` gregkh
2017-01-27 7:48 ` gregkh
2017-01-27 17:47 ` Kani, Toshimitsu
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