[OpenAFS-devel] Re: BUG: unable to handle kernel NULL pointer

[Marc Dionne]

On Mon, May 20, 2013 at 4:41 PM, Markus Suvanto
<markus.suvanto@gmail.com> wrote:
> May 20 23:37:04 kvm1 kernel: RIP: 0010:[<0000000000000000>]  [<
>   (null)>]           (null)
> May 20 23:37:04 kvm1 kernel: RSP: 0018:ffff88011623ba50  EFLAGS: 00010246
> May 20 23:37:04 kvm1 kernel: RAX: ffffffff813401c0 RBX:
> ffff88011623bad8 RCX: 000000000001461e
> May 20 23:37:04 kvm1 kernel: RDX: 0000000000014681 RSI:
> ffffea0004375840 RDI: 0000000000000000
> May 20 23:37:04 kvm1 kernel: RBP: ffffea0004375880 R08:
> ffffea0004375880 R09: 0000000000013746
> May 20 23:37:04 kvm1 kernel: R10: 000000000000095e R11:
> 0000000000000000 R12: ffffea0004375840
> May 20 23:37:04 kvm1 kernel: R13: ffff88011716f078 R14:
> 0000000000000001 R15: 0000000000000000
> May 20 23:37:04 kvm1 kernel: FS:  00007f4404ccc700(0000)
> GS:ffff88011fc80000(0000) knlGS:0000000000000000
> May 20 23:37:04 kvm1 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> May 20 23:37:04 kvm1 kernel: CR2: 0000000000000000 CR3:
> 00000001191a4000 CR4: 00000000000007e0
> May 20 23:37:04 kvm1 kernel: DR0: 0000000000000000 DR1:
> 0000000000000000 DR2: 0000000000000000
> May 20 23:37:04 kvm1 kernel: DR3: 0000000000000000 DR6:
> 00000000ffff0ff0 DR7: 0000000000000400
> May 20 23:37:04 kvm1 kernel: Process ld (pid: 1599, threadinfo
> ffff88011623a000, task ffff88011215d280)
> May 20 23:37:04 kvm1 kernel: Stack:
> May 20 23:37:04 kvm1 kernel:  ffffffffa0807a32 ffff880119a01300
> 0000000018608b40 ffffc90001478800
> May 20 23:37:04 kvm1 kernel:  ffffea0004375880 0000000000001000
> ffff880118608b40 ffffc90001478800
> May 20 23:37:04 kvm1 kernel:  ffff880119a01300 0000000000000001
> ffffffffa08082c8 ffff88011fff8c00
> May 20 23:37:04 kvm1 kernel: Call Trace:
> May 20 23:37:04 kvm1 kernel:  [<ffffffffa0807a32>] ?
> afs_linux_read_cache.isra.20+0x182/0x340 [libafs]
> May 20 23:37:04 kvm1 kernel:  [<ffffffffa08082c8>] ?
> afs_linux_fillpage+0x6d8/0x9b0 [libafs]
> May 20 23:37:04 kvm1 kernel:  [<ffffffffa0796d95>] ?
> afs_InitReq+0x85/0xf0 [libafs]
> May 20 23:37:04 kvm1 kernel:  [<ffffffffa0809472>] ?
> afs_linux_readpage+0x192/0x490 [libafs]
> May 20 23:37:04 kvm1 kernel:  [<ffffffff810b1db4>] ?
> add_to_page_cache_locked+0x84/0xe0
> May 20 23:37:04 kvm1 kernel:  [<ffffffff810b2f64>] ?
> generic_file_aio_read+0x204/0x6e0
> May 20 23:37:04 kvm1 kernel:  [<ffffffffa0804fa2>] ?
> afs_linux_aio_read+0xf2/0x290 [libafs]
> May 20 23:37:04 kvm1 kernel:  [<ffffffff810d2e6e>] ? handle_pte_fault+0xae/0x9a0
> May 20 23:37:04 kvm1 kernel:  [<ffffffff81100494>] ? do_sync_read+0x94/0xd0
> May 20 23:37:04 kvm1 kernel:  [<ffffffff81100c9d>] ? vfs_read+0x16d/0x190
> May 20 23:37:04 kvm1 kernel:  [<ffffffff81100e70>] ? sys_read+0x50/0xa0
> May 20 23:37:04 kvm1 kernel:  [<ffffffff8132dea9>] ?
> system_call_fastpath+0x16/0x1b
> May 20 23:37:04 kvm1 kernel: Code:  Bad RIP value.
> May 20 23:37:04 kvm1 kernel:  RSP <ffff88011623ba50>
> May 20 23:37:04 kvm1 kernel: CR2: 0000000000000000
> May 20 23:37:04 kvm1 kernel: ---[ end trace cd4f184e9e79af88 ]---
>
> -Markus

Thanks for testing - for tmpfs, this is because the readpage()
function is no longer implemented by tmpfs as of kernel 3.1, and some
of the optimizations rely on this being available.  I have a
workaround to detect this and bypass the affected code, but we'll have
to see if it's something that people think is suitable for 1.6.3.

I'll also see if I can test the btrfs case - not something I have
tested recently.

Marc