Messages in this thread | | | Date | Sun, 12 Jun 2011 08:04:21 +0900 | Subject | Re: [PATCH] [BUGFIX] update mm->owner even if no next owner. | From | Hiroyuki Kamezawa <> |
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2011/6/12 Andrea Arcangeli <aarcange@redhat.com>: > On Sat, Jun 11, 2011 at 07:51:36PM +0200, Johannes Weiner wrote: >> This is a problem with the patch, but I think Kame's analysis and >> approach to fix it are still correct. > > I agree with Kame's analysis too. This explains why removing the > mmap_sem read mode introduced the problem, it was quite some > unexpected subtleness not apparent to the naked eye, as memcg didn't > explicitly relay on mmap_sem but it did implicitly during exit because > of the __khugepaged_exit waiting if we were collapsing an hugepage... > > So the fix is safe because the task struct is freed with > delayed_put_task_struct and that won't run until we rcu_read_unlock > after mem_cgroup_from_task. > > Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> >
Thank you all.
Regards, -Kame
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