diff options
| author | Konstantin Khlebnikov <khlebnikov@openvz.org> | 2012-06-07 23:21:14 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-06-07 23:43:55 +0200 |
| commit | 40af1bbdca47e5c8a2044039bb78ca8fd8b20f94 (patch) | |
| tree | 70b5a21579f8b0137c09e54d523246d84be93430 /fs | |
| parent | btree: catch NULL value before it does harm (diff) | |
| download | linux-40af1bbdca47e5c8a2044039bb78ca8fd8b20f94.tar.xz linux-40af1bbdca47e5c8a2044039bb78ca8fd8b20f94.zip | |
mm: correctly synchronize rss-counters at exit/exec
mm->rss_stat counters have per-task delta: task->rss_stat. Before
changing task->mm pointer the kernel must flush this delta with
sync_mm_rss().
do_exit() already calls sync_mm_rss() to flush the rss-counters before
committing the rss statistics into task->signal->maxrss, taskstats,
audit and other stuff. Unfortunately the kernel does this before
calling mm_release(), which can call put_user() for processing
task->clear_child_tid. So at this point we can trigger page-faults and
task->rss_stat becomes non-zero again. As a result mm->rss_stat becomes
inconsistent and check_mm() will print something like this:
| BUG: Bad rss-counter state mm:ffff88020813c380 idx:1 val:-1
| BUG: Bad rss-counter state mm:ffff88020813c380 idx:2 val:1
This patch moves sync_mm_rss() into mm_release(), and moves mm_release()
out of do_exit() and calls it earlier. After mm_release() there should
be no pagefaults.
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org> [3.4.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/exec.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c index a79786a8d2c8..b926ed19301e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -819,7 +819,6 @@ static int exec_mmap(struct mm_struct *mm) /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(old_mm); mm_release(tsk, old_mm); if (old_mm) { |