On Tue, May 24, 2016 at 11:22:02AM +0200, Michal Hocko wrote:

On Tue 24-05-16 12:01:42, Vladimir Davydov wrote:

quoted

On Tue, May 24, 2016 at 10:47:37AM +0200, Michal Hocko wrote:

quoted

On Tue 24-05-16 11:43:19, Vladimir Davydov wrote:

quoted

On Mon, May 23, 2016 at 07:44:43PM +0200, Michal Hocko wrote:

quoted

On Mon 23-05-16 19:02:10, Vladimir Davydov wrote:

quoted

mem_cgroup_oom may be invoked multiple times while a process is handling
a page fault, in which case current->memcg_in_oom will be overwritten
leaking the previously taken css reference.

Have you seen this happening? I was under impression that the page fault
paths that have oom enabled will not retry allocations.

filemap_fault will, for readahead.

I thought that the readahead is __GFP_NORETRY so we do not trigger OOM
killer.

Hmm, interesting. We do allocate readahead pages with __GFP_NORETRY, but
we add them to page cache and hence charge with GFP_KERNEL or GFP_NOFS
mask, see __do_page_cache_readahaed -> read_pages.

I guess we do not want to trigger OOM just because of readahead. What do

I agree this is how it should ideally work. Not sure if anybody would
bother in practice.

you think about the following? I will cook up a full patch if this
(untested) looks ok.

It won't work for most filesystems as they define custom ->readpages. I
wonder if it'd be OK to patch them all not to trigger oom.

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