Re: mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page

[Michal Hocko]

On Thu 21-05-20 16:11:11, Naresh Kamboju wrote:
> On Thu, 21 May 2020 at 15:25, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> >
> > On Wed 20-05-20 20:09:06, Chris Down wrote:
> > > Hi Naresh,
> > >
> > > Naresh Kamboju writes:
> > > > As a part of investigation on this issue LKFT teammate Anders Roxell
> > > > git bisected the problem and found bad commit(s) which caused this problem.
> > > >
> > > > The following two patches have been reverted on next-20200519 and retested the
> > > > reproducible steps and confirmed the test case mkfs -t ext4 got PASS.
> > > > ( invoked oom-killer is gone now)
> > > >
> > > > Revert "mm, memcg: avoid stale protection values when cgroup is above
> > > > protection"
> > > >    This reverts commit 23a53e1c02006120f89383270d46cbd040a70bc6.
> > > >
> > > > Revert "mm, memcg: decouple e{low,min} state mutations from protection
> > > > checks"
> > > >    This reverts commit 7b88906ab7399b58bb088c28befe50bcce076d82.
> > >
> > > Thanks Anders and Naresh for tracking this down and reverting.
> > >
> > > I'll take a look tomorrow. I don't see anything immediately obviously wrong
> > > in either of those commits from a (very) cursory glance, but they should
> > > only be taking effect if protections are set.
> >
> > Agreed. If memory.{low,min} is not used then the patch should be
> > effectively a nop. Btw. do you see the problem when booting with
> > cgroup_disable=memory kernel command line parameter?
> 
> With extra kernel command line parameters, cgroup_disable=memory
> I have noticed a differ problem now.
> 
> + mkfs -t ext4 /dev/disk/by-id/ata-TOSHIBA_MG04ACA100N_Y8NRK0BPF6XF
> mke2fs 1.43.8 (1-Jan-2018)
> Creating filesystem with 244190646 4k blocks and 61054976 inodes
> Filesystem UUID: 3bb1a285-2cb4-44b4-b6e8-62548f3ac620
> Superblock backups stored on blocks:
> 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
> 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
> 102400000, 214990848
> Allocating group tables:    0/7453                           done
> Writing inode tables:    0/7453                           done
> Creating journal (262144 blocks): [   35.502102] BUG: kernel NULL
> pointer dereference, address: 000000c8
> [   35.508372] #PF: supervisor read access in kernel mode
> [   35.513506] #PF: error_code(0x0000) - not-present page
> [   35.518638] *pde = 00000000
> [   35.521514] Oops: 0000 [#1] SMP
> [   35.524652] CPU: 0 PID: 145 Comm: kswapd0 Not tainted
> 5.7.0-rc6-next-20200519+ #1
> [   35.532121] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
> 2.2 05/23/2018
> [   35.539507] EIP: mem_cgroup_get_nr_swap_pages+0x28/0x60

Could you get faddr2line for this offset?

-- 
Michal Hocko
SUSE Labs