* [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
@ 2011-08-01 15:28 ` Caspar Zhang
0 siblings, 0 replies; 7+ messages in thread
From: Caspar Zhang @ 2011-08-01 15:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Caspar Zhang, linux-mm, KOSAKI Motohiro, LKML
commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
which made vma_merge() always return NULL.
Re-tested the patched kernel with the reproducer provided in commit
9d8cebd, got correct result like below:
addr = 0x7ffa5aaa2000
[snip]
7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
---
mm/mempolicy.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8b57173..b1f70d6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
struct vm_area_struct *prev;
struct vm_area_struct *vma;
int err = 0;
- pgoff_t pgoff;
unsigned long vmstart;
unsigned long vmend;
@@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
vmstart = max(start, vma->vm_start);
vmend = min(end, vma->vm_end);
- pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
- vma->anon_vma, vma->vm_file, pgoff, new_pol);
+ vma->anon_vma, vma->vm_file, vma->vm_pgoff,
+ new_pol);
if (prev) {
vma = prev;
next = vma->vm_next;
--
1.7.6
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
@ 2011-08-01 15:28 ` Caspar Zhang
0 siblings, 0 replies; 7+ messages in thread
From: Caspar Zhang @ 2011-08-01 15:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Caspar Zhang, linux-mm, KOSAKI Motohiro, LKML
commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
which made vma_merge() always return NULL.
Re-tested the patched kernel with the reproducer provided in commit
9d8cebd, got correct result like below:
addr = 0x7ffa5aaa2000
[snip]
7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
---
mm/mempolicy.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8b57173..b1f70d6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
struct vm_area_struct *prev;
struct vm_area_struct *vma;
int err = 0;
- pgoff_t pgoff;
unsigned long vmstart;
unsigned long vmend;
@@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
vmstart = max(start, vma->vm_start);
vmend = min(end, vma->vm_end);
- pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
- vma->anon_vma, vma->vm_file, pgoff, new_pol);
+ vma->anon_vma, vma->vm_file, vma->vm_pgoff,
+ new_pol);
if (prev) {
vma = prev;
next = vma->vm_next;
--
1.7.6
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
2011-08-01 15:28 ` Caspar Zhang
@ 2011-08-26 21:23 ` Andrew Morton
-1 siblings, 0 replies; 7+ messages in thread
From: Andrew Morton @ 2011-08-26 21:23 UTC (permalink / raw)
To: Caspar Zhang; +Cc: linux-mm, KOSAKI Motohiro, LKML
On Mon, 1 Aug 2011 23:28:55 +0800
Caspar Zhang <caspar@casparzhang.com> wrote:
> commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
> mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
> which made vma_merge() always return NULL.
>
> Re-tested the patched kernel with the reproducer provided in commit
> 9d8cebd, got correct result like below:
>
> addr = 0x7ffa5aaa2000
> [snip]
> 7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
> 7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
>
Please also describe the output before the patch is applied, and tell
us what you believe is wrong with it?
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
> struct vm_area_struct *prev;
> struct vm_area_struct *vma;
> int err = 0;
> - pgoff_t pgoff;
> unsigned long vmstart;
> unsigned long vmend;
>
> @@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
> vmstart = max(start, vma->vm_start);
> vmend = min(end, vma->vm_end);
>
> - pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
> - vma->anon_vma, vma->vm_file, pgoff, new_pol);
> + vma->anon_vma, vma->vm_file, vma->vm_pgoff,
> + new_pol);
> if (prev) {
> vma = prev;
> next = vma->vm_next;
> --
> 1.7.6
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
@ 2011-08-26 21:23 ` Andrew Morton
0 siblings, 0 replies; 7+ messages in thread
From: Andrew Morton @ 2011-08-26 21:23 UTC (permalink / raw)
To: Caspar Zhang; +Cc: linux-mm, KOSAKI Motohiro, LKML
On Mon, 1 Aug 2011 23:28:55 +0800
Caspar Zhang <caspar@casparzhang.com> wrote:
> commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
> mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
> which made vma_merge() always return NULL.
>
> Re-tested the patched kernel with the reproducer provided in commit
> 9d8cebd, got correct result like below:
>
> addr = 0x7ffa5aaa2000
> [snip]
> 7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
> 7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
>
Please also describe the output before the patch is applied, and tell
us what you believe is wrong with it?
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
> struct vm_area_struct *prev;
> struct vm_area_struct *vma;
> int err = 0;
> - pgoff_t pgoff;
> unsigned long vmstart;
> unsigned long vmend;
>
> @@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
> vmstart = max(start, vma->vm_start);
> vmend = min(end, vma->vm_end);
>
> - pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
> - vma->anon_vma, vma->vm_file, pgoff, new_pol);
> + vma->anon_vma, vma->vm_file, vma->vm_pgoff,
> + new_pol);
> if (prev) {
> vma = prev;
> next = vma->vm_next;
> --
> 1.7.6
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
2011-08-26 21:23 ` Andrew Morton
@ 2011-08-27 2:50 ` Caspar Zhang
-1 siblings, 0 replies; 7+ messages in thread
From: Caspar Zhang @ 2011-08-27 2:50 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, KOSAKI Motohiro, LKML
On 08/27/2011 05:23 AM, Andrew Morton wrote:
> On Mon, 1 Aug 2011 23:28:55 +0800
> Caspar Zhang<caspar@casparzhang.com> wrote:
>
>> commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
>> mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
>> which made vma_merge() always return NULL.
>>
>> Re-tested the patched kernel with the reproducer provided in commit
>> 9d8cebd, got correct result like below:
>>
>> addr = 0x7ffa5aaa2000
>> [snip]
>> 7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
>> 7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
>>
>
> Please also describe the output before the patch is applied, and tell
> us what you believe is wrong with it?
Sure. Before the patch applied, we are getting a result like:
addr = 0x7fa58f00c000
[snip]
7fa58f00c000-7fa58f00d000 rw-p 00000000 00:00 0
7fa58f00d000-7fa58f00e000 rw-p 00000000 00:00 0
7fa58f00e000-7fa58f00f000 rw-p 00000000 00:00 0
here 7fa58f00c000->7fa58f00f000 we get 3 VMAs which are expected to be
merged described in commit 9d8cebd.
commit 9d8cebd says:
-------------------------------------------------------------------
commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4
Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Fri Mar 5 13:41:57 2010 -0800
mm: fix mbind vma merge problem
Strangely, current mbind() doesn't merge vma with neighbor vma
although it's possible.
Unfortunately, many vma can reduce performance...
This patch fixes it.
-------------------------------------------------------------------
mbind_range() invokes vma_range() to merge current VMA with its successor:
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
vma->anon_vma, vma->vm_file, pgoff, new_pol);
in vma_merge(), it should go into:
if (next && end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags,
anon_vma, file, pgoff+pglen)) {
...
}
while in can_vma_merge_before(), we have:
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
if (is_mergeable_vma(vma, file, vm_flags) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
if (vma->vm_pgoff == vm_pgoff)
return 1;
}
return 0;
}
to make can_vma_merge_before() return 1, we should have (next->vm_pgoff
== pgoff + pglen) in vma_merge(), i.e., pgoff should be the page offset
of *current* VMA.
However from the current codes in mbind_range(), we get:
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
start is the beginning addr of the range, so here pgoff will always be
the page offset of the beginning VMA, that makes merging VMAs impossible
in mbind_range().
To solve this bug, we simply need to pass vma->pgoff instead of the
calculated pgoff value to vma_merge().
Thanks,
Caspar
>
>> --- a/mm/mempolicy.c
>> +++ b/mm/mempolicy.c
>> @@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
>> struct vm_area_struct *prev;
>> struct vm_area_struct *vma;
>> int err = 0;
>> - pgoff_t pgoff;
>> unsigned long vmstart;
>> unsigned long vmend;
>>
>> @@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
>> vmstart = max(start, vma->vm_start);
>> vmend = min(end, vma->vm_end);
>>
>> - pgoff = vma->vm_pgoff + ((start - vma->vm_start)>> PAGE_SHIFT);
>> prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
>> - vma->anon_vma, vma->vm_file, pgoff, new_pol);
>> + vma->anon_vma, vma->vm_file, vma->vm_pgoff,
>> + new_pol);
>> if (prev) {
>> vma = prev;
>> next = vma->vm_next;
>> --
>> 1.7.6
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
@ 2011-08-27 2:50 ` Caspar Zhang
0 siblings, 0 replies; 7+ messages in thread
From: Caspar Zhang @ 2011-08-27 2:50 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, KOSAKI Motohiro, LKML
On 08/27/2011 05:23 AM, Andrew Morton wrote:
> On Mon, 1 Aug 2011 23:28:55 +0800
> Caspar Zhang<caspar@casparzhang.com> wrote:
>
>> commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
>> mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
>> which made vma_merge() always return NULL.
>>
>> Re-tested the patched kernel with the reproducer provided in commit
>> 9d8cebd, got correct result like below:
>>
>> addr = 0x7ffa5aaa2000
>> [snip]
>> 7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
>> 7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
>>
>
> Please also describe the output before the patch is applied, and tell
> us what you believe is wrong with it?
Sure. Before the patch applied, we are getting a result like:
addr = 0x7fa58f00c000
[snip]
7fa58f00c000-7fa58f00d000 rw-p 00000000 00:00 0
7fa58f00d000-7fa58f00e000 rw-p 00000000 00:00 0
7fa58f00e000-7fa58f00f000 rw-p 00000000 00:00 0
here 7fa58f00c000->7fa58f00f000 we get 3 VMAs which are expected to be
merged described in commit 9d8cebd.
commit 9d8cebd says:
-------------------------------------------------------------------
commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4
Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Fri Mar 5 13:41:57 2010 -0800
mm: fix mbind vma merge problem
Strangely, current mbind() doesn't merge vma with neighbor vma
although it's possible.
Unfortunately, many vma can reduce performance...
This patch fixes it.
-------------------------------------------------------------------
mbind_range() invokes vma_range() to merge current VMA with its successor:
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
vma->anon_vma, vma->vm_file, pgoff, new_pol);
in vma_merge(), it should go into:
if (next && end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags,
anon_vma, file, pgoff+pglen)) {
...
}
while in can_vma_merge_before(), we have:
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
if (is_mergeable_vma(vma, file, vm_flags) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
if (vma->vm_pgoff == vm_pgoff)
return 1;
}
return 0;
}
to make can_vma_merge_before() return 1, we should have (next->vm_pgoff
== pgoff + pglen) in vma_merge(), i.e., pgoff should be the page offset
of *current* VMA.
However from the current codes in mbind_range(), we get:
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
start is the beginning addr of the range, so here pgoff will always be
the page offset of the beginning VMA, that makes merging VMAs impossible
in mbind_range().
To solve this bug, we simply need to pass vma->pgoff instead of the
calculated pgoff value to vma_merge().
Thanks,
Caspar
>
>> --- a/mm/mempolicy.c
>> +++ b/mm/mempolicy.c
>> @@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
>> struct vm_area_struct *prev;
>> struct vm_area_struct *vma;
>> int err = 0;
>> - pgoff_t pgoff;
>> unsigned long vmstart;
>> unsigned long vmend;
>>
>> @@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
>> vmstart = max(start, vma->vm_start);
>> vmend = min(end, vma->vm_end);
>>
>> - pgoff = vma->vm_pgoff + ((start - vma->vm_start)>> PAGE_SHIFT);
>> prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
>> - vma->anon_vma, vma->vm_file, pgoff, new_pol);
>> + vma->anon_vma, vma->vm_file, vma->vm_pgoff,
>> + new_pol);
>> if (prev) {
>> vma = prev;
>> next = vma->vm_next;
>> --
>> 1.7.6
--
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] 7+ messages in thread
* [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge
@ 2011-07-31 17:47 Caspar Zhang
0 siblings, 0 replies; 7+ messages in thread
From: Caspar Zhang @ 2011-07-31 17:47 UTC (permalink / raw)
To: linux-mm; +Cc: Caspar Zhang
commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 didn't real fix the
mbind vma merge problem due to wrong pgoff value passing to vma_merge(),
which made vma_merge() always return NULL.
Re-tested the patched kernel with the reproducer provided in commit
9d8cebd, got correct result like below:
addr = 0x7ffa5aaa2000
[snip]
7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]
Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
---
mm/mempolicy.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8b57173..b1f70d6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,7 +636,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
struct vm_area_struct *prev;
struct vm_area_struct *vma;
int err = 0;
- pgoff_t pgoff;
unsigned long vmstart;
unsigned long vmend;
@@ -649,9 +648,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
vmstart = max(start, vma->vm_start);
vmend = min(end, vma->vm_end);
- pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
- vma->anon_vma, vma->vm_file, pgoff, new_pol);
+ vma->anon_vma, vma->vm_file, vma->vm_pgoff,
+ new_pol);
if (prev) {
vma = prev;
next = vma->vm_next;
--
1.7.6
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2011-08-27 2:52 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-08-01 15:28 [PATCH] mm/mempolicy.c: fix pgoff in mbind vma merge Caspar Zhang
2011-08-01 15:28 ` Caspar Zhang
2011-08-26 21:23 ` Andrew Morton
2011-08-26 21:23 ` Andrew Morton
2011-08-27 2:50 ` Caspar Zhang
2011-08-27 2:50 ` Caspar Zhang
-- strict thread matches above, loose matches on Subject: below --
2011-07-31 17:47 Caspar Zhang
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