[Devel] WARNING at mm/slub.c

[Konstantin Khorenko]

On 03/20/2017 11:11 AM, Denis Kirjanov wrote:
> On 3/16/17, Denis Kirjanov <dkirjanov at cloudlinux.com> wrote:
>> Hi guys,
>>
>> with the kernel rh7-3.10.0-327.36.1.vz7.18.7 we're seeing the
>> following WARNING while running LTP test suite:
>>
>> [11796.576981] WARNING: at mm/slub.c:1252
>> slab_pre_alloc_hook.isra.42.part.43+0x15/0x17()
>>
>> [11796.591008] Call Trace:
>> [11796.592065]  [<ffffffff8164c468>] dump_stack+0x19/0x1b
>> [11796.593076]  [<ffffffff8107b850>] warn_slowpath_common+0x70/0xb0
>> [11796.594228]  [<ffffffff8107b99a>] warn_slowpath_null+0x1a/0x20
>> [11796.595442]  [<ffffffff81649469>]
>> slab_pre_alloc_hook.isra.42.part.43+0x15/0x17
>> [11796.596686]  [<ffffffff811d8b68>] kmem_cache_alloc_trace+0x58/0x230
>> [11796.597965]  [<ffffffff813126ee>] ? kmapset_new+0x1e/0x50
>> [11796.599224]  [<ffffffff813126ee>] kmapset_new+0x1e/0x50
>> [11796.600433]  [<ffffffff8127c7ba>] __sysfs_add_one+0x4a/0xb0
>> [11796.601431]  [<ffffffff8127c83b>] sysfs_add_one+0x1b/0xd0
>> [11796.602451]  [<ffffffff8127baa7>] sysfs_add_file_mode+0xb7/0x100
>> [11796.603449]  [<ffffffff8127bb1a>] sysfs_create_file+0x2a/0x30
>> [11796.604461]  [<ffffffff812fe12c>] kobject_add_internal+0x16c/0x2f0
>> [11796.605503]  [<ffffffff812fe5b5>] kobject_add+0x75/0xd0
>> [11796.606627]  [<ffffffff811d8d17>] ? kmem_cache_alloc_trace+0x207/0x230
>> [11796.607655]  [<ffffffffa0563091>] __link_block_group+0xe1/0x120 [btrfs]
>> [11796.608634]  [<ffffffffa05661a0>] btrfs_make_block_group+0x150/0x270
>> [btrfs]
>> [11796.609701]  [<ffffffffa059fd5f>] __btrfs_alloc_chunk+0x67f/0x8a0
>> [btrfs]
>> [11796.610756]  [<ffffffffa05a2eb4>] btrfs_alloc_chunk+0x34/0x40 [btrfs]
>> [11796.611800]  [<ffffffffa055d62f>] do_chunk_alloc+0x23f/0x410 [btrfs]
>> [11796.612954]  [<ffffffffa055e61a>]
>> btrfs_check_data_free_space+0xea/0x280 [btrfs]
>> [11796.614008]  [<ffffffffa05898a1>] __btrfs_buffered_write+0x151/0x5c0
>> [btrfs]
>> [11796.615153]  [<ffffffffa058d056>] btrfs_file_aio_write+0x246/0x560
>> [btrfs]
>> [11796.616141]  [<ffffffff811eae92>] ?
>> __mem_cgroup_commit_charge+0x152/0x350
>> [11796.617220]  [<ffffffff811faff0>] do_sync_write+0x90/0xe0
>> [11796.618253]  [<ffffffff811fb81d>] vfs_write+0xbd/0x1e0
>> [11796.619224]  [<ffffffff811fc2bf>] SyS_write+0x7f/0xe0
>> [11796.620185]  [<ffffffff8165ccc9>] system_call_fastpath+0x16/0x1b
>> [11796.621145] ---[ end trace 1437311f89b9e3c6 ]---
>>
>
> Guys, I've found your commit:
>
> commit 149819fef38230c95f4d6c644061bc8b0dcdd51d
> Author: Vladimir Davydov <vdavydov at parallels.com>
> Date:   Fri Jun 5 13:20:02 2015 +0400
>
>     mm/fs: Port diff-mm-debug-memallocation-caused-fs-reentrance
>
>     Enable the debug once again, as the issue it found has been fixed:
>     https://jira.sw.ru/browse/PSBM-34112
>
>     Previous commit: 255427905323ac97a3c9b2d5acb2bf21ea2b31f6.
>
>     Author: Dmitry Monakhov
>     Email: dmonakhov at openvz.org
>     Subject: mm: debug memallocation caused fs reentrance
>     Date: Sun, 9 Nov 2014 11:53:14 +0400
>
> But I can't open a link to figure out the original reason for the patch.

Did not get your question.
If the question is about inability to open a link, then sorry for that but it's an internal jira id.

If this is an indirect question about how the issue has been fixed so we could return back the debug,
then there were a bunch of patches ported from mainstream, probably the one you needed is:

commit 4fdb5543183d027a19805b72025b859af73d0863
Author: Dmitry Monakhov <dmonakhov at openvz.org>
Date:   Tue Nov 25 13:08:04 2014 -0500

     ext4: cleanup GFP flags inside resize path


If the question was "why the debug patch was added at all?", then Dima can explain.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team