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authorThomas Richter <tmricht@linux.ibm.com>2019-10-21 10:33:54 +0200
committerIngo Molnar <mingo@kernel.org>2019-10-21 11:31:24 +0200
commit5e6c3c7b1ec217c1c4c95d9148182302b9969b97 (patch)
treea67ba9618fb379e2eb8016d5d8d914f8353f1617
parentMerge tag 'perf-urgent-for-mingo-5.4-20191017' of git://git.kernel.org/pub/sc... (diff)
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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>
-rw-r--r--kernel/events/core.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9ec0b0bfddbd..f5d7950d1931 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);