Re: [Bug #13941] x86 Geode issue
From: Martin-Ãric Racine
Date: Fri Sep 11 2009 - 08:36:35 EST
2009年8月17日 Ingo Molnar <mingo@xxxxxxx>:
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* Ingo Molnar <mingo@xxxxxxx> wrote:
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> * Martin-Ãric Racine <q-funk@xxxxxx> wrote:
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> > On Thu, Aug 13, 2009 at 9:34 PM, Rafael J. Wysocki<rjw@xxxxxxx> wrote:
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> > > On Thursday 13 August 2009, Martin-Ãric Racine wrote:
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> > >> On Thu, Aug 13, 2009 at 5:54 PM, Rafael J. Wysocki<rjw@xxxxxxx> wrote:
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> > >> > On Thursday 13 August 2009, Martin-Ãric Racine wrote:
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> > >> >> 2009年8月13日 Martin-Ãric Racine <q-funk@xxxxxx>:
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> > >> >> > On Thu, Aug 13, 2009 at 12:07 PM, Ingo Molnar<mingo@xxxxxxx> wrote:
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> > >> >> >> * Martin-Ãric Racine <q-funk@xxxxxx> wrote:
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> > >> >> >>> Yes, this bug is still valid.
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> > >> >> >>>
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> > >> >> >>> Ubuntu kernel team member Leann Ogasawara and I are slowly
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> > >> >> >>> bisecting our way through the changes that took place since 2.6.30
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> > >> >> >>> to find the commit that introduced this regression. Please stay
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> > >> >> >>> tuned.
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> > >> >> >>
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> > >> >> >> hm, the only outright Geode related commit was:
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> > >> >> >>
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> > >> >> >> Âd6c585a: x86: geode: Mark mfgpt irq IRQF_TIMER to prevent resume failure
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> > >> >> >>
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> > >> >> >> the jpg at:
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> > >> >> >>
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> > >> >> >> Âhttp://launchpadlibrarian.net/28892781/00002.jpg
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> > >> >> >>
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> > >> >> >> is very out of focus - but what i could decypher suggests a
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> > >> >> >> pagefault crash in the VFS code, in generic_delete_inode().
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> > >> >>
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> > >> >> This one might be a bit better:
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> > >> >>
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> > >> >> http://launchpadlibrarian.net/30267494/2.6.31-5.24.jpg
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> > >
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> > > Hmm. ÂThis looks like a sysfs oops to my untrained eye.
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> >
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> > The bisect I did with Leann Ogasawara has narrowed the kernel panic
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> > down to the following:
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> >
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> > commit f19d4a8fa6f9b6ccf54df0971c97ffcaa390b7b0
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> > Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
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> > Date: Mon Jun 8 19:50:45 2009 -0400
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> >
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> > Â Â add caching of ACLs in struct inode
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> >
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> > Â Â No helpers, no conversions yet.
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> >
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> > Â Â Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
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> Weird. If the functions do what their name suggests, i.e. if
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> inode_init_always() is an always called constructor and if
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> destroy_inode() is an unconditional destructor then this patch
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> should have no functional effect on the VFS side.
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>
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> It increases the size of struct inode, so if you have some old
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> module (built to an older version of fs.h) still around it might
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> corrupt your inode data structure.
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> Or the size change might trigger some dormant bug. It might move a
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> critical inode right into the path of a pre-existing (but not
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> visibly crash-triggering) data corruption.
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> The possibilities on the 'weird bug' front are endless - the
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> crash/oops itself should be turned into text, posted here and
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> analyzed.
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Btw., before you invest any time into the 'weird crash' theory, i'd
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suggest to double check the bisection result:
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Âf19d4a8fa6f9b6ccf54df0971c97ffcaa390b7b0 Â Âcrashes
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Âf19d4a8fa6f9b6ccf54df0971c97ffcaa390b7b0~1 Âboots fine
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You can save yourself from a lot of head scratching that way - the
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bisection result looks weird. (albeit plausible - a VFS crash points
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to a VFS commit.)
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_Maybe_ the bisection is just off a little bit (there was a
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bisection mistake in the last few steps), and the real buggy commit
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is one of the nearby ones:
We double checked again last week with fresh builds and validated that
the above result is correct.
What puzzles us is the start of the crash:
BUG: unable to handle kernel paging request at ffffb4ff
IP: [<c01f716b>] __destroy_inode+0x4b/0x80
*pde = 00810067 *pte = 00000000
Oops: 0000 [#1] SMP
last sysfs file: /sys/power/resume
Any ideas?
Martin-Ãric
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