On Tue, May 24, 2016 at 11:22:02AM +0200, Michal Hocko wrote: > On Tue 24-05-16 12:01:42, Vladimir Davydov wrote: > > On Tue, May 24, 2016 at 10:47:37AM +0200, Michal Hocko wrote: > > > On Tue 24-05-16 11:43:19, Vladimir Davydov wrote: > > > > On Mon, May 23, 2016 at 07:44:43PM +0200, Michal Hocko wrote: > > > > > On Mon 23-05-16 19:02:10, Vladimir Davydov wrote: > > > > > > 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>