Re: 2.6.15-rt20, "bad page state", jackd

[Nick Piggin <nickpiggin@yahoo.com.au>]

Heiko Carstens wrote:

> Actually I have a bug report that looks quite the same. Happens on s390x
> with lots of I/O stress. But that is against vanilla 2.6.16-rc4 + additional
> patches. I need to ask to reproduce that with a plain vanilla kernel, so
> that a git bisect search might help to figure out what is wrong.
> Unfortunately it seems to take hours before we hit the bug.
> 

It is different because yours is coming from __alloc_pages, so if there
are no previous warnings then it means it wasn't corrupted before last
being freed, so it is a use-after-free bug. I'm surprised at how many
fields have been modified though (mapping, count, mapcount).

PG_error is set, which might mean it is a bug in an error handling path
that doesn't trigger very often.

> <0>Bad page state in process 'blast'
> <0>page:0000000000507d00 flags:0x000000060000002a mapping:00000000007570b0 mapcount:1 count:8
> <0>Trying to fix it up, but a reboot is needed
> <0>Backtrace:
> <4>0000000006e93750 0000000000000000 0000000000773780 0700000000007c7a 
> <4>       0000000000000001 000000000025f878 000000000025f878 0000000000104840 
> <4>       0000000000000000 000000060000002a 0000000000000000 0000000000518d50 
> <4>       000000000000000c 0000000000000008 0000000006e936f8 0000000006e93770 
> <4>       000000000044e1f0 0000000000104840 0000000006e936f8 0000000006e93738 
> <4>Call Trace:
> <4>([<0000000000104870>] dump_stack+0x2b8/0x374)
> <4> [<00000000001a97de>] get_page_from_freelist+0x72e/0x8e8
> <4> [<00000000001a9aa8>] __alloc_pages+0x110/0x324
> <4> [<00000000001b37a0>] page_cache_readahead+0xf6c/0x11e4
> <4> [<000000000019f870>] do_generic_mapping_read+0x150/0x828
> <4> [<00000000001a07f4>] generic_file_aio_read+0x1f8/0x258
> <4> [<00000000001fa844>] do_sync_read+0x130/0x1bc
> <4> [<00000000001fc230>] sys_read+0x170/0x3b8
> <4> [<000000000010fb20>] sysc_tracego+0xe/0x14
> <4> [<0000020000043a84>] 0x20000043a84
> 
> Heiko

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SUSE Labs, Novell Inc.
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