linux-kernel - Re: linux-next: xfs metadata corruption since 30 March

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Date:   Tue, 31 Mar 2020 22:13:42 -0400
From:   Qian Cai <cai@....pw>
To:     Dave Chinner <david@...morbit.com>
Cc:     "Darrick J. Wong" <darrick.wong@...cle.com>,
        Christoph Hellwig <hch@....de>, linux-xfs@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: xfs metadata corruption since 30 March



> On Mar 31, 2020, at 6:13 PM, Dave Chinner <david@...morbit.com> wrote:
> 
> On Tue, Mar 31, 2020 at 05:57:24PM -0400, Qian Cai wrote:
>> Ever since two days ago, linux-next starts to trigger xfs metadata corruption
>> during compilation workloads on both powerpc and arm64,
> 
> Is this on an existing filesystem, or a new filesystem?

New.

> 
>> I suspect it could be one of those commits,
>> 
>> https://lore.kernel.org/linux-xfs/20200328182533.GM29339@magnolia/
>> 
>> Especially, those commits that would mark corruption more aggressively?
>> 
>>      [8d57c21600a5] xfs: add a function to deal with corrupt buffers post-verifiers
>>      [e83cf875d67a] xfs: xfs_buf_corruption_error should take __this_address
>>      [ce99494c9699] xfs: fix buffer corruption reporting when xfs_dir3_free_header_check fails
>>      [1cb5deb5bc09] xfs: don't ever return a stale pointer from __xfs_dir3_free_read
>>      [6fb5aac73310] xfs: check owner of dir3 free blocks
>>      [a10c21ed5d52] xfs: check owner of dir3 data blocks
>>      [1b2c1a63b678] xfs: check owner of dir3 blocks
>>      [2e107cf869ee] xfs: mark dir corrupt when lookup-by-hash fails
>>      [806d3909a57e] xfs: mark extended attr corrupt when lookup-by-hash fails
> 
> Doubt it - they only add extra detection code and these:
> 
>> [29331.182313][  T665] XFS (dm-2): Metadata corruption detected at xfs_inode_buf_verify+0x2b8/0x350 [xfs], xfs_inode block 0xa9b97900 xfs_inode_buf_verify
>> xfs_inode_buf_verify at fs/xfs/libxfs/xfs_inode_buf.c:101
>> [29331.182373][  T665] XFS (dm-2): Unmount and run xfs_repair
>> [29331.182386][  T665] XFS (dm-2): First 128 bytes of corrupted metadata buffer:
>> [29331.182402][  T665] 00000000: 2f 2a 20 53 50 44 58 2d 4c 69 63 65 6e 73 65 2d  /* SPDX-License-
>> [29331.182426][  T665] 00000010: 49 64 65 6e 74 69 66 69 65 72 3a 20 47 50 4c 2d  Identifier: GPL-
> 
> Would get caught by the existing  verifiers as they aren't valid
> metadata at all.
> 
> Basically, you are getting file data where there should be inode
> metadata. First thing to do is fix the existing corruptions with
> xfs_repair - please post the entire output so we can see what was
> corruption and what it fixed.


# xfs_repair -v /dev/mapper/rhel_hpe--apollo--cn99xx--11-home 
Phase 1 - find and verify superblock...
        - block cache size set to 4355512 entries
Phase 2 - using internal log
        - zero log...
zero_log: head block 793608 tail block 786824
ERROR: The filesystem has valuable metadata changes in a log which needs to
be replayed.  Mount the filesystem to replay the log, and unmount it before
re-running xfs_repair.  If you are unable to mount the filesystem, then use
the -L option to destroy the log and attempt a repair.
Note that destroying the log may cause corruption -- please attempt a mount
of the filesystem before doing this.

# mount /dev/mapper/rhel_hpe--apollo--cn99xx--11-home /home/
# umount /home/
# xfs_repair -v /dev/mapper/rhel_hpe--apollo--cn99xx--11-home 
Phase 1 - find and verify superblock...
        - block cache size set to 4355512 entries
Phase 2 - using internal log
        - zero log...
zero_log: head block 793624 tail block 793624
        - scan filesystem freespace and inode maps...
        - found root inode chunk
Phase 3 - for each AG...
        - scan and clear agi unlinked lists...
        - process known inodes and perform inode discovery...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - process newly discovered inodes...
Phase 4 - check for duplicate blocks...
        - setting up duplicate extent list...
        - check for inodes claiming duplicate blocks...
        - agno = 0
        - agno = 2
        - agno = 1
        - agno = 3
Phase 5 - rebuild AG headers and trees...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - reset superblock...
Phase 6 - check inode connectivity...
        - resetting contents of realtime bitmap and summary inodes
        - traversing filesystem ...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - traversal finished ...
        - moving disconnected inodes to lost+found ...
Phase 7 - verify and correct link counts...

        XFS_REPAIR Summary    Tue Mar 31 22:10:54 2020

Phase		Start		End		Duration
Phase 1:	03/31 22:10:45	03/31 22:10:45	
Phase 2:	03/31 22:10:45	03/31 22:10:45	
Phase 3:	03/31 22:10:45	03/31 22:10:46	1 second
Phase 4:	03/31 22:10:46	03/31 22:10:53	7 seconds
Phase 5:	03/31 22:10:53	03/31 22:10:53	
Phase 6:	03/31 22:10:53	03/31 22:10:53	
Phase 7:	03/31 22:10:53	03/31 22:10:53	

Total run time: 8 seconds
done
> 
> Then if the problem is still reproducable, I suspect you are going
> to have to bisect it. i.e. run test, get corruption, mark bisect
> bad, run xfs_repair or mkfs to fix mess, install new kernel, run
> test again....
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@...morbit.com