On Fri 02-08-19 16:28:25, Masoud Sharbiani wrote: > > > > On Aug 2, 2019, at 12:14 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > 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. > > I was unable to use cgroups2. I’ve created the new control group, but the attempt to move a running process into it fails with ‘Device or resource busy’. Have you enabled the memory controller for the hierarchy? Please read Documentation/admin-guide/cgroup-v2.rst for more information. -- Michal Hocko SUSE Labs
