On Fri 02-08-19 11:00:55, Masoud Sharbiani wrote: > > > > On Aug 2, 2019, at 7:41 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > On Fri 02-08-19 07:18:17, Masoud Sharbiani wrote: > >> > >> > >>> On Aug 2, 2019, at 12:40 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > >>> > >>> On Thu 01-08-19 11:04:14, Masoud Sharbiani wrote: > >>>> Hey folks, > >>>> I’ve come across an issue that affects most of 4.19, 4.20 and 5.2 linux-stable kernels that has only been fixed in 5.3-rc1. > >>>> It was introduced by > >>>> > >>>> 29ef680 memcg, oom: move out_of_memory back to the charge path > >>> > >>> This commit shouldn't really change the OOM behavior for your particular > >>> test case. It would have changed MAP_POPULATE behavior but your usage is > >>> triggering the standard page fault path. The only difference with > >>> 29ef680 is that the OOM killer is invoked during the charge path rather > >>> than on the way out of the page fault. > >>> > >>> Anyway, I tried to run your test case in a loop and leaker always ends > >>> up being killed as expected with 5.2. See the below oom report. There > >>> must be something else going on. How much swap do you have on your > >>> system? > >> > >> I do not have swap defined. > > > > OK, I have retested with swap disabled and again everything seems to be > > working as expected. The oom happens earlier because I do not have to > > wait for the swap to get full. > > > > In my tests (with the script provided), it only loops 11 iterations before hanging, and uttering the soft lockup message. > > > > Which fs do you use to write the file that you mmap? > > /dev/sda3 on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota) > > Part of the soft lockup path actually specifies that it is going through __xfs_filemap_fault(): Right, I have just missed that. [...] > If I switch the backing file to a ext4 filesystem (separate hard drive), it OOMs. > > > If I switch the file used to /dev/zero, it OOMs: > … > Todal sum was 0. Loop count is 11 > Buffer is @ 0x7f2b66c00000 > ./test-script-devzero.sh: line 16: 3561 Killed ./leaker -p 10240 -c 100000 > > > > Or could you try to > > simplify your test even further? E.g. does everything work as expected > > when doing anonymous mmap rather than file backed one? > > It also OOMs with MAP_ANON. > > Hope that helps. It helps to focus more on the xfs reclaim path. Just to be sure, is there any difference if you use cgroup v2? I do not expect to be but just to be sure there are no v1 artifacts. -- Michal Hocko SUSE Labs
