* [PATCH] perf/core: Fix tracking of auxiliary trace buffer allocation
@ 2019-10-21 8:33 Thomas Richter
2019-10-21 9:35 ` [tip: perf/urgent] perf/aux: " tip-bot2 for Thomas Richter
0 siblings, 1 reply; 3+ messages in thread
From: Thomas Richter @ 2019-10-21 8:33 UTC (permalink / raw)
To: linux-perf-users, linux-kernel, songliubraving, hechaol, acme,
mingo, peterz
Cc: heiko.carstens, gor, Thomas Richter
commit d44248a41337 ("perf/core: Rework memory accounting in perf_mmap()")
breaks auxiliary trace buffer tracking.
I run command 'perf record -e rbd000' to record samples and saving
them in the **auxiliary** trace buffer. The value of 'locked_vm' becomes
negative after all trace buffers have been allocated and released:
During allocation the values increase
[52.250027] perf_mmap user->locked_vm:0x87 pinned_vm:0x0 ret:0
[52.250115] perf_mmap user->locked_vm:0x107 pinned_vm:0x0 ret:0
[52.250251] perf_mmap user->locked_vm:0x188 pinned_vm:0x0 ret:0
[52.250326] perf_mmap user->locked_vm:0x208 pinned_vm:0x0 ret:0
[52.250441] perf_mmap user->locked_vm:0x289 pinned_vm:0x0 ret:0
[52.250498] perf_mmap user->locked_vm:0x309 pinned_vm:0x0 ret:0
[52.250613] perf_mmap user->locked_vm:0x38a pinned_vm:0x0 ret:0
[52.250715] perf_mmap user->locked_vm:0x408 pinned_vm:0x2 ret:0
[52.250834] perf_mmap user->locked_vm:0x408 pinned_vm:0x83 ret:0
[52.250915] perf_mmap user->locked_vm:0x408 pinned_vm:0x103 ret:0
[52.251061] perf_mmap user->locked_vm:0x408 pinned_vm:0x184 ret:0
[52.251146] perf_mmap user->locked_vm:0x408 pinned_vm:0x204 ret:0
[52.251299] perf_mmap user->locked_vm:0x408 pinned_vm:0x285 ret:0
[52.251383] perf_mmap user->locked_vm:0x408 pinned_vm:0x305 ret:0
[52.251544] perf_mmap user->locked_vm:0x408 pinned_vm:0x386 ret:0
[52.251634] perf_mmap user->locked_vm:0x408 pinned_vm:0x406 ret:0
[52.253018] perf_mmap user->locked_vm:0x408 pinned_vm:0x487 ret:0
[52.253197] perf_mmap user->locked_vm:0x408 pinned_vm:0x508 ret:0
[52.253374] perf_mmap user->locked_vm:0x408 pinned_vm:0x589 ret:0
[52.253550] perf_mmap user->locked_vm:0x408 pinned_vm:0x60a ret:0
[52.253726] perf_mmap user->locked_vm:0x408 pinned_vm:0x68b ret:0
[52.253903] perf_mmap user->locked_vm:0x408 pinned_vm:0x70c ret:0
[52.254084] perf_mmap user->locked_vm:0x408 pinned_vm:0x78d ret:0
[52.254263] perf_mmap user->locked_vm:0x408 pinned_vm:0x80e ret:0
The value of user->locked_vm increases to a limit then the memory
is tracked by pinned_vm.
During deallocation the size is subtracted from pinned_vm until
it hits a limit. Then a larger value is subtracted from locked_vm
leading to a large number (because of type unsigned):
[64.267797] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x78d
[64.267826] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x70c
[64.267848] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x68b
[64.267869] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x60a
[64.267891] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x589
[64.267911] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x508
[64.267933] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x487
[64.267952] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x406
[64.268883] perf_mmap_close mmap_user->locked_vm:0x307 pinned_vm:0x406
[64.269117] perf_mmap_close mmap_user->locked_vm:0x206 pinned_vm:0x406
[64.269433] perf_mmap_close mmap_user->locked_vm:0x105 pinned_vm:0x406
[64.269536] perf_mmap_close mmap_user->locked_vm:0x4 pinned_vm:0x404
[64.269797] perf_mmap_close mmap_user->locked_vm:0xffffffffffffff84 pinned_vm:0x303
[64.270105] perf_mmap_close mmap_user->locked_vm:0xffffffffffffff04 pinned_vm:0x202
[64.270374] perf_mmap_close mmap_user->locked_vm:0xfffffffffffffe84 pinned_vm:0x101
[64.270628] perf_mmap_close mmap_user->locked_vm:0xfffffffffffffe04 pinned_vm:0x0
This value sticks for the user until system is rebooted, causing
follow-on system calls using locked_vm resource limit to fail.
Note: There is no issue using the normal trace buffer.
In fact the issue is in perf_mmap_close(). During allocation auxiliary
trace buffer memory is either traced as 'extra' and added to 'pinned_vm'
or trace as 'user_extra' and added to 'locked_vm'. This applies for
normal trace buffers and auxiliary trace buffer.
However in function perf_mmap_close() all auxiliary trace buffer is
subtraced from 'locked_vm' and never from 'pinned_vm'. This breaks the
ballance.
Fixes: d44248a41337 ("perf/core: Rework memory accounting in perf_mmap()")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
---
kernel/events/core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9ec0b0bfddbd..90ba23043af0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5607,8 +5607,12 @@ static void perf_mmap_close(struct vm_area_struct *vma)
perf_pmu_output_stop(event);
/* now it's safe to free the pages */
- atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm);
- atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
+ if (!rb->aux_mmap_locked)
+ atomic_long_sub(rb->aux_nr_pages,
+ &mmap_user->locked_vm);
+ else
+ atomic64_sub(rb->aux_mmap_locked,
+ &vma->vm_mm->pinned_vm);
/* this has to be the last one */
rb_free_aux(rb);
--
2.21.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [tip: perf/urgent] perf/aux: Fix tracking of auxiliary trace buffer allocation
2019-10-21 8:33 [PATCH] perf/core: Fix tracking of auxiliary trace buffer allocation Thomas Richter
@ 2019-10-21 9:35 ` tip-bot2 for Thomas Richter
2019-11-15 16:06 ` Alexander Shishkin
0 siblings, 1 reply; 3+ messages in thread
From: tip-bot2 for Thomas Richter @ 2019-10-21 9:35 UTC (permalink / raw)
To: linux-tip-commits
Cc: Thomas Richter, Peter Zijlstra, Alexander Shishkin,
Arnaldo Carvalho de Melo, Jiri Olsa, Linus Torvalds,
Mark Rutland, Namhyung Kim, Peter Zijlstra, Thomas Gleixner,
acme, gor, hechaol, heiko.carstens, linux-perf-users,
songliubraving, Ingo Molnar, Borislav Petkov, linux-kernel
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 5e6c3c7b1ec217c1c4c95d9148182302b9969b97
Gitweb: https://git.kernel.org/tip/5e6c3c7b1ec217c1c4c95d9148182302b9969b97
Author: Thomas Richter <tmricht@linux.ibm.com>
AuthorDate: Mon, 21 Oct 2019 10:33:54 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Mon, 21 Oct 2019 11:31:24 +02:00
perf/aux: Fix tracking of auxiliary trace buffer allocation
The following commit from the v5.4 merge window:
d44248a41337 ("perf/core: Rework memory accounting in perf_mmap()")
... breaks auxiliary trace buffer tracking.
If I run command 'perf record -e rbd000' to record samples and saving
them in the **auxiliary** trace buffer then the value of 'locked_vm' becomes
negative after all trace buffers have been allocated and released:
During allocation the values increase:
[52.250027] perf_mmap user->locked_vm:0x87 pinned_vm:0x0 ret:0
[52.250115] perf_mmap user->locked_vm:0x107 pinned_vm:0x0 ret:0
[52.250251] perf_mmap user->locked_vm:0x188 pinned_vm:0x0 ret:0
[52.250326] perf_mmap user->locked_vm:0x208 pinned_vm:0x0 ret:0
[52.250441] perf_mmap user->locked_vm:0x289 pinned_vm:0x0 ret:0
[52.250498] perf_mmap user->locked_vm:0x309 pinned_vm:0x0 ret:0
[52.250613] perf_mmap user->locked_vm:0x38a pinned_vm:0x0 ret:0
[52.250715] perf_mmap user->locked_vm:0x408 pinned_vm:0x2 ret:0
[52.250834] perf_mmap user->locked_vm:0x408 pinned_vm:0x83 ret:0
[52.250915] perf_mmap user->locked_vm:0x408 pinned_vm:0x103 ret:0
[52.251061] perf_mmap user->locked_vm:0x408 pinned_vm:0x184 ret:0
[52.251146] perf_mmap user->locked_vm:0x408 pinned_vm:0x204 ret:0
[52.251299] perf_mmap user->locked_vm:0x408 pinned_vm:0x285 ret:0
[52.251383] perf_mmap user->locked_vm:0x408 pinned_vm:0x305 ret:0
[52.251544] perf_mmap user->locked_vm:0x408 pinned_vm:0x386 ret:0
[52.251634] perf_mmap user->locked_vm:0x408 pinned_vm:0x406 ret:0
[52.253018] perf_mmap user->locked_vm:0x408 pinned_vm:0x487 ret:0
[52.253197] perf_mmap user->locked_vm:0x408 pinned_vm:0x508 ret:0
[52.253374] perf_mmap user->locked_vm:0x408 pinned_vm:0x589 ret:0
[52.253550] perf_mmap user->locked_vm:0x408 pinned_vm:0x60a ret:0
[52.253726] perf_mmap user->locked_vm:0x408 pinned_vm:0x68b ret:0
[52.253903] perf_mmap user->locked_vm:0x408 pinned_vm:0x70c ret:0
[52.254084] perf_mmap user->locked_vm:0x408 pinned_vm:0x78d ret:0
[52.254263] perf_mmap user->locked_vm:0x408 pinned_vm:0x80e ret:0
The value of user->locked_vm increases to a limit then the memory
is tracked by pinned_vm.
During deallocation the size is subtracted from pinned_vm until
it hits a limit. Then a larger value is subtracted from locked_vm
leading to a large number (because of type unsigned):
[64.267797] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x78d
[64.267826] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x70c
[64.267848] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x68b
[64.267869] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x60a
[64.267891] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x589
[64.267911] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x508
[64.267933] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x487
[64.267952] perf_mmap_close mmap_user->locked_vm:0x408 pinned_vm:0x406
[64.268883] perf_mmap_close mmap_user->locked_vm:0x307 pinned_vm:0x406
[64.269117] perf_mmap_close mmap_user->locked_vm:0x206 pinned_vm:0x406
[64.269433] perf_mmap_close mmap_user->locked_vm:0x105 pinned_vm:0x406
[64.269536] perf_mmap_close mmap_user->locked_vm:0x4 pinned_vm:0x404
[64.269797] perf_mmap_close mmap_user->locked_vm:0xffffffffffffff84 pinned_vm:0x303
[64.270105] perf_mmap_close mmap_user->locked_vm:0xffffffffffffff04 pinned_vm:0x202
[64.270374] perf_mmap_close mmap_user->locked_vm:0xfffffffffffffe84 pinned_vm:0x101
[64.270628] perf_mmap_close mmap_user->locked_vm:0xfffffffffffffe04 pinned_vm:0x0
This value sticks for the user until system is rebooted, causing
follow-on system calls using locked_vm resource limit to fail.
Note: There is no issue using the normal trace buffer.
In fact the issue is in perf_mmap_close(). During allocation auxiliary
trace buffer memory is either traced as 'extra' and added to 'pinned_vm'
or trace as 'user_extra' and added to 'locked_vm'. This applies for
normal trace buffers and auxiliary trace buffer.
However in function perf_mmap_close() all auxiliary trace buffer is
subtraced from 'locked_vm' and never from 'pinned_vm'. This breaks the
ballance.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: gor@linux.ibm.com
Cc: hechaol@fb.com
Cc: heiko.carstens@de.ibm.com
Cc: linux-perf-users@vger.kernel.org
Cc: songliubraving@fb.com
Fixes: d44248a41337 ("perf/core: Rework memory accounting in perf_mmap()")
Link: https://lkml.kernel.org/r/20191021083354.67868-1-tmricht@linux.ibm.com
[ Minor readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9ec0b0b..f5d7950 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5607,8 +5607,10 @@ static void perf_mmap_close(struct vm_area_struct *vma)
perf_pmu_output_stop(event);
/* now it's safe to free the pages */
- atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm);
- atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
+ if (!rb->aux_mmap_locked)
+ atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm);
+ else
+ atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
/* this has to be the last one */
rb_free_aux(rb);
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [tip: perf/urgent] perf/aux: Fix tracking of auxiliary trace buffer allocation
2019-10-21 9:35 ` [tip: perf/urgent] perf/aux: " tip-bot2 for Thomas Richter
@ 2019-11-15 16:06 ` Alexander Shishkin
0 siblings, 0 replies; 3+ messages in thread
From: Alexander Shishkin @ 2019-11-15 16:06 UTC (permalink / raw)
To: tip-bot2 for Thomas Richter, linux-tip-commits
Cc: Thomas Richter, Peter Zijlstra, Arnaldo Carvalho de Melo,
Jiri Olsa, Linus Torvalds, Mark Rutland, Namhyung Kim,
Peter Zijlstra, Thomas Gleixner, acme, gor, hechaol,
heiko.carstens, linux-perf-users, songliubraving, Ingo Molnar,
Borislav Petkov, linux-kernel, alexander.shishkin
"tip-bot2 for Thomas Richter" <tip-bot2@linutronix.de> writes:
> /* now it's safe to free the pages */
> - atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm);
> - atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
> + if (!rb->aux_mmap_locked)
> + atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm);
> + else
> + atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
This only works correctly when rb->aux_mmap_locked is either equal to
rb->aux_nr_pages or zero. Otherwise, it leaks
rb->aux_nr_pages - rb->aux_mmap_locked
in the locked_vm permanently.
Regards,
--
Alex
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-10-21 8:33 [PATCH] perf/core: Fix tracking of auxiliary trace buffer allocation Thomas Richter
2019-10-21 9:35 ` [tip: perf/urgent] perf/aux: " tip-bot2 for Thomas Richter
2019-11-15 16:06 ` Alexander Shishkin
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