Re: [PATCH for 3.2.34] memcg: do not trigger OOM fromadd_to_page_cache_locked

[Michal Hocko]

On Fri 08-02-13 17:29:18, Michal Hocko wrote:
[...]
> OK, I have checked the allocator slow path and you are right even
> GFP_KERNEL will not fail. This can lead to similar deadlocks - e.g.
> OOM killed task blocked on down_write(mmap_sem) while the page fault
> handler holding mmap_sem for reading and allocating a new page without
> any progress.

And now that I think about it some more it sounds like it shouldn't be
possible because allocator would fail because it would see
TIF_MEMDIE (OOM killer kills all threads that share the same mm).
But maybe there are other locks that are dangerous, but I think that the
risk is pretty low.
-- 
Michal Hocko
SUSE Labs
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