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authorSong Liu <songliubraving@fb.com>2019-09-04 14:46:18 -0700
committerIngo Molnar <mingo@kernel.org>2019-10-09 12:44:12 +0200
commitd44248a41337731a111374822d7d4451b64e73e4 (patch)
tree00a83d5f6e5c1723c1d7a79b96ea27fdfabf6fea /kernel/events
parentf733c6b508bcaa3441ba1eacf16efb9abd47489f (diff)
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>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f953dd16a5e2..2b8265ad7bf5 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;