* [PATCH] perf: rework memory accounting in perf_mmap()
@ 2019-09-04 21:46 Song Liu
2019-09-16 19:43 ` Song Liu
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Song Liu @ 2019-09-04 21:46 UTC (permalink / raw)
To: linux-kernel; +Cc: kernel-team, Song Liu, Jie Meng, Peter Zijlstra
perf_mmap() always increases user->locked_vm. As a result, "extra" could
grow bigger than "user_extra", which doesn't make sense. Here is an
example case:
Note: Assume "user_lock_limit" is very small.
| # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
| 0 | 0 | 0 |
| 1 | user_extra | user_extra |
| 2 | 3 * user_extra | 2 * user_extra|
| 3 | 6 * user_extra | 3 * user_extra|
| 4 | 10 * user_extra | 4 * user_extra|
Fix this by maintaining proper user_extra and extra.
Reported-by: Hechao Li <hechaol@fb.com>
Cc: Jie Meng <jmeng@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
kernel/events/core.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0463c1151bae..a0120bdbce17 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5585,7 +5585,8 @@ static void perf_mmap_close(struct vm_area_struct *vma)
* undo the VM accounting.
*/
- atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm);
+ atomic_long_sub((size >> PAGE_SHIFT) + 1 - mmap_locked,
+ &mmap_user->locked_vm);
atomic64_sub(mmap_locked, &vma->vm_mm->pinned_vm);
free_uid(mmap_user);
@@ -5729,8 +5730,20 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
user_locked = atomic_long_read(&user->locked_vm) + user_extra;
- if (user_locked > user_lock_limit)
+ if (user_locked <= user_lock_limit) {
+ /* charge all to locked_vm */
+ } else if (atomic_long_read(&user->locked_vm) >= user_lock_limit) {
+ /* charge all to pinned_vm */
+ extra = user_extra;
+ user_extra = 0;
+ } else {
+ /*
+ * charge locked_vm until it hits user_lock_limit;
+ * charge the rest from pinned_vm
+ */
extra = user_locked - user_lock_limit;
+ user_extra -= extra;
+ }
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
--
2.17.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-09-04 21:46 [PATCH] perf: rework memory accounting in perf_mmap() Song Liu
@ 2019-09-16 19:43 ` Song Liu
2019-09-16 20:10 ` Hechao Li
2019-09-30 9:02 ` Peter Zijlstra
2019-10-09 12:59 ` [tip: perf/urgent] perf/core: Rework " tip-bot2 for Song Liu
2 siblings, 1 reply; 8+ messages in thread
From: Song Liu @ 2019-09-16 19:43 UTC (permalink / raw)
To: LKML, Peter Zijlstra; +Cc: Kernel Team, Jie Meng, Hechao Li
Hi Peter,
> On Sep 4, 2019, at 2:46 PM, Song Liu <songliubraving@fb.com> wrote:
>
> perf_mmap() always increases user->locked_vm. As a result, "extra" could
> grow bigger than "user_extra", which doesn't make sense. Here is an
> example case:
>
> Note: Assume "user_lock_limit" is very small.
> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
> | 0 | 0 | 0 |
> | 1 | user_extra | user_extra |
> | 2 | 3 * user_extra | 2 * user_extra|
> | 3 | 6 * user_extra | 3 * user_extra|
> | 4 | 10 * user_extra | 4 * user_extra|
>
> Fix this by maintaining proper user_extra and extra.
>
> Reported-by: Hechao Li <hechaol@fb.com>
> Cc: Jie Meng <jmeng@fb.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Song Liu <songliubraving@fb.com>
Could you please share your feedbacks/comments on this one?
Thanks,
Song
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-09-16 19:43 ` Song Liu
@ 2019-09-16 20:10 ` Hechao Li
2019-09-30 5:33 ` Song Liu
0 siblings, 1 reply; 8+ messages in thread
From: Hechao Li @ 2019-09-16 20:10 UTC (permalink / raw)
To: Song Liu; +Cc: LKML, Peter Zijlstra, Kernel Team, Jie Meng
Song Liu <songliubraving@fb.com> wrote on Mon [2019-Sep-16 12:43:16 -0700]:
> Hi Peter,
>
> > On Sep 4, 2019, at 2:46 PM, Song Liu <songliubraving@fb.com> wrote:
> >
> > perf_mmap() always increases user->locked_vm. As a result, "extra" could
> > grow bigger than "user_extra", which doesn't make sense. Here is an
> > example case:
> >
> > Note: Assume "user_lock_limit" is very small.
> > | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
> > | 0 | 0 | 0 |
> > | 1 | user_extra | user_extra |
> > | 2 | 3 * user_extra | 2 * user_extra|
> > | 3 | 6 * user_extra | 3 * user_extra|
> > | 4 | 10 * user_extra | 4 * user_extra|
> >
> > Fix this by maintaining proper user_extra and extra.
> >
> > Reported-by: Hechao Li <hechaol@fb.com>
> > Cc: Jie Meng <jmeng@fb.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Signed-off-by: Song Liu <songliubraving@fb.com>
>
> Could you please share your feedbacks/comments on this one?
>
> Thanks,
> Song
The change looks good to me. Thanks, Song.
Reviewed-By: Hechao Li <hechaol@fb.com>
Hechao
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-09-16 20:10 ` Hechao Li
@ 2019-09-30 5:33 ` Song Liu
0 siblings, 0 replies; 8+ messages in thread
From: Song Liu @ 2019-09-30 5:33 UTC (permalink / raw)
To: Hechao Li; +Cc: LKML, Peter Zijlstra, Kernel Team, Jie Meng
> On Sep 16, 2019, at 1:10 PM, Hechao Li <hechaol@fb.com> wrote:
>
> Song Liu <songliubraving@fb.com> wrote on Mon [2019-Sep-16 12:43:16 -0700]:
>> Hi Peter,
>>
>>> On Sep 4, 2019, at 2:46 PM, Song Liu <songliubraving@fb.com> wrote:
>>>
>>> perf_mmap() always increases user->locked_vm. As a result, "extra" could
>>> grow bigger than "user_extra", which doesn't make sense. Here is an
>>> example case:
>>>
>>> Note: Assume "user_lock_limit" is very small.
>>> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
>>> | 0 | 0 | 0 |
>>> | 1 | user_extra | user_extra |
>>> | 2 | 3 * user_extra | 2 * user_extra|
>>> | 3 | 6 * user_extra | 3 * user_extra|
>>> | 4 | 10 * user_extra | 4 * user_extra|
>>>
>>> Fix this by maintaining proper user_extra and extra.
>>>
>>> Reported-by: Hechao Li <hechaol@fb.com>
>>> Cc: Jie Meng <jmeng@fb.com>
>>> Cc: Peter Zijlstra <peterz@infradead.org>
>>> Signed-off-by: Song Liu <songliubraving@fb.com>
>>
>> Could you please share your feedbacks/comments on this one?
>>
>> Thanks,
>> Song
>
> The change looks good to me. Thanks, Song.
>
> Reviewed-By: Hechao Li <hechaol@fb.com>
Thanks Hechao!
Hi Peter,
Does this fix look good to you?
Thanks,
Song
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-09-04 21:46 [PATCH] perf: rework memory accounting in perf_mmap() Song Liu
2019-09-16 19:43 ` Song Liu
@ 2019-09-30 9:02 ` Peter Zijlstra
2019-10-07 16:31 ` Song Liu
2019-10-09 12:59 ` [tip: perf/urgent] perf/core: Rework " tip-bot2 for Song Liu
2 siblings, 1 reply; 8+ messages in thread
From: Peter Zijlstra @ 2019-09-30 9:02 UTC (permalink / raw)
To: Song Liu; +Cc: linux-kernel, kernel-team, Jie Meng
On Wed, Sep 04, 2019 at 02:46:18PM -0700, Song Liu wrote:
> perf_mmap() always increases user->locked_vm. As a result, "extra" could
> grow bigger than "user_extra", which doesn't make sense. Here is an
> example case:
>
> Note: Assume "user_lock_limit" is very small.
> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
> | 0 | 0 | 0 |
> | 1 | user_extra | user_extra |
> | 2 | 3 * user_extra | 2 * user_extra|
> | 3 | 6 * user_extra | 3 * user_extra|
> | 4 | 10 * user_extra | 4 * user_extra|
>
> Fix this by maintaining proper user_extra and extra.
Aah, indeed.
Also, this code is unreadable (which is mostly my own fault I suppose)
:/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-09-30 9:02 ` Peter Zijlstra
@ 2019-10-07 16:31 ` Song Liu
2019-10-07 16:56 ` Peter Zijlstra
0 siblings, 1 reply; 8+ messages in thread
From: Song Liu @ 2019-10-07 16:31 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: open list, Kernel Team, Jie Meng, Hechao Li
Hi Peter,
> On Sep 30, 2019, at 2:02 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Sep 04, 2019 at 02:46:18PM -0700, Song Liu wrote:
>> perf_mmap() always increases user->locked_vm. As a result, "extra" could
>> grow bigger than "user_extra", which doesn't make sense. Here is an
>> example case:
>>
>> Note: Assume "user_lock_limit" is very small.
>> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
>> | 0 | 0 | 0 |
>> | 1 | user_extra | user_extra |
>> | 2 | 3 * user_extra | 2 * user_extra|
>> | 3 | 6 * user_extra | 3 * user_extra|
>> | 4 | 10 * user_extra | 4 * user_extra|
>>
>> Fix this by maintaining proper user_extra and extra.
>
> Aah, indeed.
Thanks for the feedback!
>
> Also, this code is unreadable (which is mostly my own fault I suppose)
> :/
How does this patch look to you? Is it ready to merge?
Thanks,
Song
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] perf: rework memory accounting in perf_mmap()
2019-10-07 16:31 ` Song Liu
@ 2019-10-07 16:56 ` Peter Zijlstra
0 siblings, 0 replies; 8+ messages in thread
From: Peter Zijlstra @ 2019-10-07 16:56 UTC (permalink / raw)
To: Song Liu; +Cc: open list, Kernel Team, Jie Meng, Hechao Li
On Mon, Oct 07, 2019 at 04:31:37PM +0000, Song Liu wrote:
> Hi Peter,
>
> > On Sep 30, 2019, at 2:02 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Wed, Sep 04, 2019 at 02:46:18PM -0700, Song Liu wrote:
> >> perf_mmap() always increases user->locked_vm. As a result, "extra" could
> >> grow bigger than "user_extra", which doesn't make sense. Here is an
> >> example case:
> >>
> >> Note: Assume "user_lock_limit" is very small.
> >> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
> >> | 0 | 0 | 0 |
> >> | 1 | user_extra | user_extra |
> >> | 2 | 3 * user_extra | 2 * user_extra|
> >> | 3 | 6 * user_extra | 3 * user_extra|
> >> | 4 | 10 * user_extra | 4 * user_extra|
> >>
> >> Fix this by maintaining proper user_extra and extra.
> >
> > Aah, indeed.
>
> Thanks for the feedback!
>
> >
> > Also, this code is unreadable (which is mostly my own fault I suppose)
> > :/
>
> How does this patch look to you? Is it ready to merge?
Yes, I queued it, I'll get it into tip soon. It got held up due to me
working on some other patches, sorry about that.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [tip: perf/urgent] perf/core: Rework memory accounting in perf_mmap()
2019-09-04 21:46 [PATCH] perf: rework memory accounting in perf_mmap() Song Liu
2019-09-16 19:43 ` Song Liu
2019-09-30 9:02 ` Peter Zijlstra
@ 2019-10-09 12:59 ` tip-bot2 for Song Liu
2 siblings, 0 replies; 8+ messages in thread
From: tip-bot2 for Song Liu @ 2019-10-09 12:59 UTC (permalink / raw)
To: linux-tip-commits
Cc: Hechao Li, Song Liu, Peter Zijlstra (Intel),
kernel-team, Jie Meng, Linus Torvalds, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, linux-kernel
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: d44248a41337731a111374822d7d4451b64e73e4
Gitweb: https://git.kernel.org/tip/d44248a41337731a111374822d7d4451b64e73e4
Author: Song Liu <songliubraving@fb.com>
AuthorDate: Wed, 04 Sep 2019 14:46:18 -07:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 09 Oct 2019 12:44:12 +02:00
perf/core: Rework memory accounting in perf_mmap()
perf_mmap() always increases user->locked_vm. As a result, "extra" could
grow bigger than "user_extra", which doesn't make sense. Here is an
example case:
(Note: Assume "user_lock_limit" is very small.)
| # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm|
| 0 | 0 | 0 |
| 1 | user_extra | user_extra |
| 2 | 3 * user_extra | 2 * user_extra|
| 3 | 6 * user_extra | 3 * user_extra|
| 4 | 10 * user_extra | 4 * user_extra|
Fix this by maintaining proper user_extra and extra.
Reviewed-By: Hechao Li <hechaol@fb.com>
Reported-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <kernel-team@fb.com>
Cc: Jie Meng <jmeng@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190904214618.3795672-1-songliubraving@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/core.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f953dd1..2b8265a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5668,7 +5668,8 @@ again:
* undo the VM accounting.
*/
- atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm);
+ atomic_long_sub((size >> PAGE_SHIFT) + 1 - mmap_locked,
+ &mmap_user->locked_vm);
atomic64_sub(mmap_locked, &vma->vm_mm->pinned_vm);
free_uid(mmap_user);
@@ -5812,8 +5813,20 @@ accounting:
user_locked = atomic_long_read(&user->locked_vm) + user_extra;
- if (user_locked > user_lock_limit)
+ if (user_locked <= user_lock_limit) {
+ /* charge all to locked_vm */
+ } else if (atomic_long_read(&user->locked_vm) >= user_lock_limit) {
+ /* charge all to pinned_vm */
+ extra = user_extra;
+ user_extra = 0;
+ } else {
+ /*
+ * charge locked_vm until it hits user_lock_limit;
+ * charge the rest from pinned_vm
+ */
extra = user_locked - user_lock_limit;
+ user_extra -= extra;
+ }
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
^ permalink raw reply related [flat|nested] 8+ messages in thread
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2019-09-04 21:46 [PATCH] perf: rework memory accounting in perf_mmap() Song Liu
2019-09-16 19:43 ` Song Liu
2019-09-16 20:10 ` Hechao Li
2019-09-30 5:33 ` Song Liu
2019-09-30 9:02 ` Peter Zijlstra
2019-10-07 16:31 ` Song Liu
2019-10-07 16:56 ` Peter Zijlstra
2019-10-09 12:59 ` [tip: perf/urgent] perf/core: Rework " tip-bot2 for Song Liu
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