Re: md: bug in file raid5.c, line 1909 in 2.4.22-pre7

[Neil Brown]

On Tuesday August 19, mfedyk@xxxxxxxxxxxxx wrote:
> I have another report against rc1 also, but this is with a different line
> number and under different circumstances, but with the same hardware.
> 
> Details in dmesg file.
.....
> Aug 15 16:44:22 srv-lr2600 kernel: RAID5 conf printout:
> Aug 15 16:44:22 srv-lr2600 kernel:  --- rd:3 wd:2 fd:1
> Aug 15 16:44:22 srv-lr2600 kernel:  disk 0, s:0, o:1, n:0 rd:0 us:1 dev:hde3
> Aug 15 16:44:22 srv-lr2600 kernel:  disk 1, s:0, o:1, n:1 rd:1 us:1 dev:hdg3
> Aug 15 16:44:22 srv-lr2600 kernel:  disk 2, s:0, o:0, n:0 rd:0 us:0 dev:[dev 00:00]
> Aug 15 16:44:22 srv-lr2600 kernel: md: bug in file raid5.c, line 1909
> 
> And why did I get this bug?
> 
> Aug 15 16:44:22 srv-lr2600 kernel: 
> Aug 15 16:44:22 srv-lr2600 kernel: md:^I**********************************
> Aug 15 16:44:22 srv-lr2600 kernel: md:^I* <COMPLETE RAID STATE PRINTOUT> *
> Aug 15 16:44:22 srv-lr2600 kernel: md:^I**********************************
> Aug 15 16:44:22 srv-lr2600 kernel: md0: <hda3><hdg3><hde3> array superblock:
> Aug 15 16:44:22 srv-lr2600 kernel: md:  SB: (V:0.90.0) ID:<dea08cef.28d34b00.79cd55bc.46bdbe06> CT:3f34718d
> Aug 15 16:44:22 srv-lr2600 kernel: md:     L5 S159694016 ND:3 RD:3 md0 LO:0 CS:65536
> Aug 15 16:44:23 srv-lr2600 kernel: md:     UT:3f3d602e ST:0 AD:2 WD:3 FD:0 SD:1 CSUM:f9253789 E:0001b800
> Aug 15 16:44:23 srv-lr2600 kernel:      D  0:  DISK<N:0,hde3(33,3),R:0,S:6>
> Aug 15 16:44:23 srv-lr2600 kernel:      D  1:  DISK<N:1,hdg3(34,3),R:1,S:6>
> Aug 15 16:44:23 srv-lr2600 kernel:      D  2:  DISK<N:2,[dev 00:00](0,0),R:2,S:8>
> Aug 15 16:44:23 srv-lr2600 kernel:      D  3:  DISK<N:3,hda3(3,3),R:3,S:0>


Because descriptor 2 (D  2:) in the superblock has state
MD_DISK_REMOVED (S:8) rather and doesn't have the MD_DISK_FAULTY but
set (S:9 or S:1).
As far as I can see, the 2.4 code would never set just MD_DISK_REMOVED
(though it really should cope with it).  It is possible that the 2.6
code does.  Has this array had 2.6 running on it?  Does it have any
interesting history?

NeilBrown

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