Messages in this thread Patch in this message | | | Date | Mon, 30 Jul 2012 07:14:04 -0700 | From | tip-bot for Oleg Nesterov <> | Subject | [tip:perf/core] uprobes: Suppress uprobe_munmap() from mmput() |
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Commit-ID: 2fd611a991391a6050cbd139201a2e12fc306540 Gitweb: http://git.kernel.org/tip/2fd611a991391a6050cbd139201a2e12fc306540 Author: Oleg Nesterov <oleg@redhat.com> AuthorDate: Sun, 29 Jul 2012 20:22:31 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Mon, 30 Jul 2012 11:27:21 +0200
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> --- 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;
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