Re: Memory hotplug softlock issue

[Baoquan He <bhe@redhat.com>]

On 11/15/18 at 02:19pm, Michal Hocko wrote:
> On Thu 15-11-18 21:12:11, Baoquan He wrote:
> > On 11/15/18 at 09:30am, Michal Hocko wrote:
> [...]
> > > It would be also good to find out whether this is fs specific. E.g. does
> > > it make any difference if you use a different one for your stress
> > > testing?
> > 
> > Created a ramdisk and put stress bin there, then run stress -m 200, now
> > seems it's stuck in libc-2.28.so migrating. And it's still xfs. So now xfs
> > is a big suspect. At bottom I paste numactl printing, you can see that it's
> > the last 4G.
> > 
> > Seems it's trying to migrate libc-2.28.so, but stress program keeps trying to
> > access and activate it.
> 
> Is this still with faultaround disabled? I have seen exactly same
> pattern in the bug I am working on. It was ext4 though.

After a long time struggling, the last 2nd block where libc-2.28.so is
located is reclaimed, now it comes to the last memory block, still
stress program itself. swap migration entry has been made and trying to
unmap, now it's looping there.

[  +0.004445] migrating pfn 190ff2bb0 failed 
[  +0.000013] page:ffffea643fcaec00 count:203 mapcount:201 mapping:ffff888dfb268f48 index:0x0
[  +0.012809] shmem_aops 
[  +0.000011] name:"stress" 
[  +0.002550] flags: 0x1dfffffc008004e(referenced|uptodate|dirty|workingset|swapbacked)
[  +0.010715] raw: 01dfffffc008004e ffffea643fcaec48 ffffea643fc714c8 ffff888dfb268f48
[  +0.007828] raw: 0000000000000000 0000000000000000 000000cb000000c8 ffff888e72e92000
[  +0.007810] page->mem_cgroup:ffff888e72e92000
[  +0.004466] migrating pfn 190ff2bb1 failed 
[  +0.000013] page:ffffea643fcaec40 count:203 mapcount:201 mapping:ffff888dfb268f48 index:0x2
[  +0.014321] shmem_aops 
[  +0.000024] name:"stress" 
[  +0.002535] flags: 0x1dfffffc008004e(referenced|uptodate|dirty|workingset|swapbacked)
[  +0.010680] raw: 01dfffffc008004e ffffc900000e3d80 ffffea643fcaec08 ffff888dfb268f48
[  +0.007863] raw: 0000000000000002 0000000000000000 000000cb000000c8 ffff888e72e92000
[  +0.007828] page->mem_cgroup:ffff888e72e92000
[  +1.357302] migrating pfn 190ff1c53 failed 
[  +0.000011] page:ffffea643fc714c0 count:202 mapcount:201 mapping:ffff888e5e395109 index:0x28
[  +0.012756] anon 
[  +0.000024] flags: 0x1dfffffc008004c(uptodate|dirty|workingset|swapbacked)
[  +0.008961] raw: 01dfffffc008004c ffffea643fcaec08 ffffc900000e3d80 ffff888e5e395109
[  +0.007847] raw: 0000000000000028 0000000000000000 000000ca000000c8 ffff888e72e92000
[  +0.007844] page->mem_cgroup:ffff888e72e92000
[  +0.004455] migrating pfn 190ff2bb0 failed 
[  +0.000018] page:ffffea643fcaec00 count:203 mapcount:201 mapping:ffff888dfb268f48 index:0x0
[  +0.014392] shmem_aops 
[  +0.000010] name:"stress" 
[  +0.002565] flags: 0x1dfffffc008004e(referenced|uptodate|dirty|workingset|swapbacked)
[  +0.010675] raw: 01dfffffc008004e ffffea643fcaec48 ffffea643fc714c8 ffff888dfb268f48
[  +0.007819] raw: 0000000000000000 0000000000000000 000000cb000000c8 ffff888e72e92000
[  +0.007808] page->mem_cgroup:ffff888e72e92000
[  +0.004431] migrating pfn 190ff2bb1 failed 
[  +0.000019] page:ffffea643fcaec40 count:203 mapcount:201 mapping:ffff888dfb268f48 index:0x2
[  +0.012688] shmem_aops 
[  +0.000012] name:"stress" 
[  +0.002525] flags: 0x1dfffffc008004e(referenced|uptodate|dirty|workingset|swapbacked)
[  +0.012385] raw: 01dfffffc008004e ffffc900000e3d80 ffffea643fcaec08 ffff888dfb268f48
[  +0.007840] raw: 0000000000000002 0000000000000000 000000cb000000c8 ffff888e72e92000
[  +0.007832] page->mem_cgroup:ffff888e72e92000