Re: kernel BUG under 2.6.1-mm5

From: Jim Faulkner
Date: Mon Jan 26 2004 - 16:23:20 EST



On Mon, 26 Jan 2004, Andrey Borzenkov wrote:

> On Thursday 22 January 2004 01:48, Andrew Morton wrote:
> > Jim Faulkner <jfaulkne@xxxxxxxxxxx> wrote:
> > > Hello,
> > >
> > > I am seeing some scary looking kernel bug entries in my dmesg under
> > > 2.6.1-mm5.
> > > ...
> > >
> > > kernel BUG at fs/dcache.c:760!
> > > invalid operand: 0000 [#1]
> > > PREEMPT SMP
> > > CPU: 0
> > > EIP: 0060:[<c0179627>] Not tainted VLI
> > > EFLAGS: 00010287
> > > EIP is at d_instantiate+0x17/0x90
> > > eax: f7baf200 ebx: c1b8bac0 ecx: 000021a4 edx: 00000000
> > > esi: f7a4f868 edi: f7baf200 ebp: f7a4f840 esp: f7a79e3c
> > > ds: 007b es: 007b ss: 0068
> > > Process hotplug (pid: 24, threadinfo=f7a78000 task=c1b06d00)
> > > Stack: 00000000 f7a992e4 c1b8bac0 c1b35940 f7a78000 f7a4f840 c01ad6de
> > > f7a4f840
> > > f7baf200 f7a4f840 f7a41e1c c1bbeb40 00000000 c1b06d00 c011f5b0
> > > 00000000
> > > 00000000 f7a96d00 c1b06d00 c011bb7d 00000000 c1b06d00 c011f5b0
> > > 00000000
> > > Call Trace:
> > > [<c01ad6de>] devfs_d_revalidate_wait+0xbe/0x1b0
> > > [<c011f5b0>] default_wake_function+0x0/0x20
> > > [<c011bb7d>] do_page_fault+0x32d/0x512
> > > [<c011f5b0>] default_wake_function+0x0/0x20
> > > [<c016e868>] do_lookup+0x68/0xb0
> > > [<c016ede8>] link_path_walk+0x538/0xa30
> > > [<c016fd03>] open_namei+0x83/0x420
> > > [<c011b850>] do_page_fault+0x0/0x512
> > > [<c040d4cb>] error_code+0x2f/0x38
> > > [<c015e61e>] filp_open+0x3e/0x70
> > > [<c015eb9b>] sys_open+0x5b/0x90
> > > [<c040c992>] sysenter_past_esp+0x43/0x65
> >
> > hmm. There was a patch in that area which I have subsequently dropped
> > because it was really fixing devfs problems in the wrong place.
> >
> hmm ...
>
> > Perhaps Andrey can ask you to test a subsequent patch if he takes another
> > look at this.
>
> please try this one. This basically does the same inside of devfs. It passed
> usual sanity checks here; I cannot reproduce oops you have (do you have SMP
> system?)
>
> I appreciate if someone with more intimate knowledge of fs/namei.c comments if
> conditions in devfs_d_revalidate_wait make sense.
>
> -andrey
>

Yes, I have an SMP system.

Your patch works! I applied it to 2.6.2-rc1-mm1 (which is the last -mm
version that doesn't kernel panic on me because of an unrelated bug), and
the "kernel BUG" warning has gone away.

thanks!
Jim Faulkner
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