On Monday 07 of December 2015, John Stoffel wrote:

Arkadiusz> 4.3.0 kernel, raid6 array:

I think there's a bug in the 4.3.x and 4.4-rc3 and lower with block
merges.  I ran into these over the weekend, where v4.2.6 was stable,
but anything higher would lock up and crash on me.

Well, no crashes here.

So first step would be to make sure you get and test v4.4-rc4.

Do you know which commit there?

Arkadiusz> md7 : active raid6 sdg[10] sdad1[9] sdac1[8] sdag1[7] sdaf1[6]
sdae1[5] sdaj1[4] sdai1[3] sdah1[2] sdn1[1] Arkadiusz>       31255089152
blocks super 1.2 level 6, 512k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
Arkadiusz>       bitmap: 1/30 pages [4KB], 65536KB chunk

Arkadiusz> array had weird failure where many disks went into failed state
but Arkadiusz> remove && adding these disks "fixed" it (turns out not
really fixed it).

Arkadiusz> Unfortunately now some reads fail:

Arkadiusz> pread(4, 0x1483a00, 4096, 16003680464896) = -1 EIO (Input/output
error)

Arkadiusz> To reproduce used xfs_io
Arkadiusz>  xfs_io -d -c "pread 16003680464896 4096" /dev/md7
Arkadiusz> pread64: Input/output error
Arkadiusz> which does pread exactly as shown above.

Arkadiusz> write also fails for that area:
Arkadiusz> xfs_io -d -c "pwrite 16003680464896 4096" /dev/md7
Arkadiusz> pwrite64: Input/output error

Arkadiusz> Note that nothing is written in dmesg when that happens.

Arkadiusz> I've tried various offsets and sizes of pread and at some point
that was logged: Arkadiusz> [  848.988518] Buffer I/O error on dev md7,
logical block 3907148544, async page read

Arkadiusz> but no error from underlying devices.

Arkadiusz> List of bad blocks:
Arkadiusz> http://sprunge.us/XSWI

Arkadiusz> What can I do now?

Arkadiusz> (loosing data from that few sectors is acceptable if the rest
will be readable)

Arkadiusz> Thanks,
Arkadiusz> --
Arkadiusz> Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )
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Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )
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