On Wed 23-12-15 16:00:09, Ross Zwisler wrote:
[...]
> While running xfstests on next-20151223 I hit a pair of kernel BUGs
> that bisected to this commit:
>
> 1eb3a80d8239 ("mm, oom: introduce oom reaper")
Thank you for the report and the bisection.
> Here is a BUG produced by generic/029 when run against XFS:
>
> [ 235.751723] ------------[ cut here ]------------
> [ 235.752194] kernel BUG at mm/filemap.c:208!
This is VM_BUG_ON_PAGE(page_mapped(page), page), right? Could you attach
the full kernel log? It all smells like a race when OOM reaper tears
down the mapping and there is a truncate still in progress. But hitting
the BUG_ON just because of that doesn't make much sense to me. OOM
reaper is essentially MADV_DONTNEED. I have to think about this some
more, though, but I am in a holiday mode until early next year so please
bear with me.
[...]
> [ 235.765638] Call Trace:
> [ 235.765903] [<ffffffff811c8493>] delete_from_page_cache+0x63/0xd0
> [ 235.766513] [<ffffffff811dc3e5>] truncate_inode_page+0xa5/0x120
> [ 235.767088] [<ffffffff811dc648>] truncate_inode_pages_range+0x1a8/0x7f0
> [ 235.767725] [<ffffffff81021459>] ? sched_clock+0x9/0x10
> [ 235.768239] [<ffffffff810db37c>] ? local_clock+0x1c/0x20
> [ 235.768779] [<ffffffff811feba4>] ? unmap_mapping_range+0x64/0x130
> [ 235.769385] [<ffffffff811febb4>] ? unmap_mapping_range+0x74/0x130
> [ 235.770010] [<ffffffff810f5c3f>] ? up_write+0x1f/0x40
> [ 235.770501] [<ffffffff811febb4>] ? unmap_mapping_range+0x74/0x130
> [ 235.771092] [<ffffffff811dcd58>] truncate_pagecache+0x48/0x70
> [ 235.771646] [<ffffffff811dcdb2>] truncate_setsize+0x32/0x40
> [ 235.772276] [<ffffffff8148e972>] xfs_setattr_size+0x232/0x470
> [ 235.772839] [<ffffffff8148ec64>] xfs_vn_setattr+0xb4/0xc0
> [ 235.773369] [<ffffffff8127af87>] notify_change+0x237/0x350
> [ 235.773945] [<ffffffff81257c87>] do_truncate+0x77/0xc0
> [ 235.774446] [<ffffffff8125800f>] do_sys_ftruncate.constprop.15+0xef/0x150
> [ 235.775156] [<ffffffff812580ae>] SyS_ftruncate+0xe/0x10
> [ 235.775650] [<ffffffff81a527b2>] entry_SYSCALL_64_fastpath+0x12/0x76
> [ 235.776257] Code: 5f 5d c3 48 8b 43 20 48 8d 78 ff a8 01 48 0f 44
> fb 8b 47 48 85 c0 0f 88 2b 01 00 00 48 c7 c6 a8 57 f0 81 48 89 df e8
> fa 1a 03 00 <0f> 0b 4c 89 ce 44 89 fa 4c 89 e7 4c 89 45 b0 4c 89 4d b8
> e8 32
> [ 235.778695] RIP [<ffffffff811c81f6>] __delete_from_page_cache+0x206/0x440
> [ 235.779350] RSP <ffff8800bab83b60>
> [ 235.779694] ---[ end trace fac9dd65c4cdd828 ]---
>
> And a different BUG produced by generic/095, also with XFS:
>
> [ 609.398897] ------------[ cut here ]------------
> [ 609.399843] kernel BUG at mm/truncate.c:629!
Hmm, I do not see any BUG_ON at this line. But there is
BUG_ON(page_mapped(page)) at line 620.
> [ 609.400666] invalid opcode: 0000 [#1] SMP
> [ 609.401512] Modules linked in: nd_pmem nd_btt nd_e820 libnvdimm
> [ 609.402719] CPU: 4 PID: 26782 Comm: fio Tainted: G W
There was a warning before this triggered. The full kernel log would be
helpful as well.
[...]
> [ 609.425325] Call Trace:
> [ 609.425797] [<ffffffff811dc307>] invalidate_inode_pages2+0x17/0x20
> [ 609.426971] [<ffffffff81482167>] xfs_file_read_iter+0x297/0x300
> [ 609.428097] [<ffffffff81259ac9>] __vfs_read+0xc9/0x100
> [ 609.429073] [<ffffffff8125a319>] vfs_read+0x89/0x130
> [ 609.430010] [<ffffffff8125b418>] SyS_read+0x58/0xd0
> [ 609.430943] [<ffffffff81a527b2>] entry_SYSCALL_64_fastpath+0x12/0x76
> [ 609.432139] Code: 85 d8 fe ff ff 01 00 00 00 f6 c4 40 0f 84 59 ff
> ff ff 49 8b 47 20 48 8d 78 ff a8 01 49 0f 44 ff 8b 47 48 85 c0 0f 88
> bd 01 00 00 <0f> 0b 4d 3b 67 08 0f 85 70 ff ff ff 49 f7 07 00 18 00 00
> 74 15
[...]
> My test setup is a qemu guest machine with a pair of 4 GiB PMEM
> ramdisk test devices, one for the xfstest test disk and one for the
> scratch disk.
Is this just a plain ramdisk device or it needs a special configuration?
Is this somehow DAX related?
Thanks!
--
Michal Hocko
SUSE Labs
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