diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2012-07-29 18:22:31 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-07-30 09:27:21 (GMT) |
| commit | 2fd611a991391a6050cbd139201a2e12fc306540 (patch) | |
| tree | 8233d2ba7dd41e29c6477d4905b6fdc1e7a721e0 | |
| parent | 665605a2a207dbe1fa429b474f932d6ea138ba92 (diff) | |
| download | linux-2fd611a991391a6050cbd139201a2e12fc306540.tar.xz | |
uprobes: Suppress uprobe_munmap() from mmput()
uprobe_munmap() does get_user_pages() and it is also called from
the final mmput()->exit_mmap() path. This slows down
exit/mmput() for no reason, and I think it is simply
dangerous/wrong to try to fault-in a page into the dying mm. If
nothing else, this happens after the last sync_mm_rss(), afaics
handle_mm_fault() can change the task->rss_stat and make the
subsequent check_mm() unhappy.
Change uprobe_munmap() to check mm->mm_users != 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120729182231.GA20336@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/events/uprobes.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index bed2161..9db9cdf 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1082,6 +1082,9 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) return; + if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ + return; + if (!atomic_read(&vma->vm_mm->uprobes_state.count)) return; |