On Sun, Jul 22, 2018 at 2:03 AM Eric Sandeen <sandeen@xxxxxxxxxxx> wrote:
> On 7/20/18 3:20 AM, Filippo Giunchedi wrote:
> > To recap what we've seen, hardware bit flipping is extremely unlikely:
> > the same type of sb_fdblocks corruption has appeared on four different
> > hosts affecting at most one third of xfs filesystems per host. Also
> > the corruption looks always the same, namely the 33rd bit flipped
> > which also seems suspicious.
>
> Running a debug kernel with memory poisoning, KASAN, or something similar might
> help catch it if it's a stray memory write of some sort...
Thanks! BTW we've experienced this again on a FS at around 77% usage
and xfs_repair reports a flip in the 32nd bit (output below). We'll
enable memory poisoning on said host and see if other filesystems on
that host experience the same.
I see in the patch thread it has been mentioned this particular
condition will be checked and fixed/prevented in 4.19 though the root
cause isn't know (?)
Thanks again!
Filippo
# xfs_repair -n /dev/sdc1
Phase 1 - find and verify superblock...
Phase 2 - using internal log
- zero log...
- scan filesystem freespace and inode maps...
sb_fdblocks 4515987426, counted 221020130
- found root inode chunk
Phase 3 - for each AG...
- scan (but don't clear) agi unlinked lists...
- process known inodes and perform inode discovery...
- agno = 0
- agno = 1
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