On Friday November 10, klimov@xxxxxxxxxxx wrote: > Hello Neil, > > >> [87398.531579] blk: request botched > NB> ^^^^^^^^^^^^^^^^^^^^ > > NB> That looks bad. Possible some bug in the IDE controller or elsewhere > NB> in the block layer. Jens: What might cause that? > > NB> --snip-- > > NB> That doesn't look like raid was involved. If it was you would expect > NB> to see raid1_end_write_request or raid1_end_read_request in that > NB> trace. > So that might be the hard or soft part of IDE layer failing the > system, or a PCI problem for example? What I think is happening here (and Jens: if you could tell me how impossible this is, that would be good) is this: Some error handling somewhere in the low-level ide driver is getting confused and somehow one the sector counts in the 'struct request' is getting set wrongly. blk_recalc_rq_sectors notices this and says "blk: request botched". It tries to auto-correct by increasing rq->nr_sectors to be consistent with other counts. I'm *guessing* this is the wrong thing to do, and that it has a side-effect but bi_end_io is getting called on the Bi twice. The second time the bio has been freed and reused and the wrong b_end_io is called and it does the wrong thing. This sounds a bit far-fetched, but it is the only explanation I can come up with for the observed back trace which is: [87403.706012] [<c0103871>] error_code+0x39/0x40 [87403.710794] [<c0180e0a>] mpage_end_io_read+0x5e/0x72 [87403.716154] [<c0164af9>] bio_endio+0x56/0x7b [87403.720798] [<c0256778>] __end_that_request_first+0x1e0/0x301 [87403.726985] [<c02568a4>] end_that_request_first+0xb/0xd [87403.732699] [<c02bd73c>] __ide_end_request+0x54/0xe1 [87403.738214] [<c02bd807>] ide_end_request+0x3e/0x5c [87403.743382] [<c02c35df>] task_error+0x5b/0x97 [87403.748113] [<c02c36fa>] task_in_intr+0x6e/0xa2 [87403.753120] [<c02bf19e>] ide_intr+0xaf/0x12c [87403.757815] [<c013e5a7>] handle_IRQ_event+0x23/0x57 [87403.763135] [<c013e66f>] __do_IRQ+0x94/0xfd [87403.767802] [<c0105192>] do_IRQ+0x32/0x68 [87403.772278] [<c010372e>] common_interrupt+0x1a/0x20 i.e. bio_endio goes straight to mpage_end_io despite the face that the filesystem is mounted over md/raid1. Is the kernel compiled with CONFIG_DEBUG_SLAB=y and CONFIG_DEBUG_PAGEALLOC=y ?? They might help trigger the error earlier and so make the problem more obvious. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
