2011/9/14 Lin Ming <mlin@xxxxxxxxxxxxx>: > On Wed, Sep 14, 2011 at 12:43 AM, Simon Kirby <sim@xxxxxxxxxx> wrote: >> On Mon, Sep 12, 2011 at 03:17:00PM -0700, Simon Kirby wrote: >> >>> On Thu, Sep 08, 2011 at 03:24:20PM -0700, Simon Kirby wrote: >>> >>> > This box primarily does most of its VFS stuff over lots of NFS mounts, >>> > but has some local EXT3 filesystems. This has happened a couple of times: >>> > >>> > BUG: unable to handle kernel NULL pointer dereference at 00000000000000b8 >>>... >>> Got a few more identical Oopses on another box running slightly past >>> 3.1-rc5 (79016f648872549392d232cd648bd02298c2d2bb). It seems to be >>> do_rmdir()'s mutex_unlock() call. >>> >>> I'm building -rc6 with CONFIG_DEBUG_MUTEXES now. >> >> ...and not much more help with CONFIG_DEBUG_MUTEXES, from 3.1-rc6: >> >> BUG: unable to handle kernel NULL pointer dereference at 00000000000000a4 >> IP: [<ffffffff816adc93>] __mutex_unlock_slowpath+0x53/0x140 >> PGD 13c6c4067 PUD 2256fc067 PMD 0 >> Oops: 0002 [#1] SMP >> CPU 2 >> Modules linked in: ipmi_devintf ipmi_si ipmi_msghandler xt_recent nf_conntrack_ftp xt_state xt_owner nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 bnx2 >> >> Pid: 27658, comm: php Not tainted 3.1.0-rc6-hw-mudbg+ #32 Dell Inc. PowerEdge 1950/0TT740 >> RIP: 0010:[<ffffffff816adc93>] [<ffffffff816adc93>] __mutex_unlock_slowpath+0x53/0x140 >> RSP: 0018:ffff8800b65e1e28 EFLAGS: 00010046 >> RAX: 0000000000000100 RBX: ffff88001bcece48 RCX: ffff88001bd05348 >> RDX: 0000000040000200 RSI: ffff8800916cf6c0 RDI: 00000000000000a0 >> RBP: ffff8800b65e1e48 R08: 00000000043205bc R09: ffffea00011340c0 >> R10: 0000000000000000 R11: 0000000000000002 R12: 00000000000000a0 >> R13: 00000000000000a4 R14: 0000000000000246 R15: 00007f7fe2d15680 >> FS: 00007f7fe2e1f720(0000) GS:ffff88022fc80000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 00000000000000a4 CR3: 0000000215c16000 CR4: 00000000000006e0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 >> Process php (pid: 27658, threadinfo ffff8800b65e0000, task ffff8800175d4320) >> Stack: >> ffff88001bcece48 00000000fffffffe ffff8800916cf6c0 00007f7fe2d146a8 >> ffff8800b65e1e58 ffffffff816add89 ffff8800b65e1e88 ffffffff8110ec70 >> ffff8800b65e1e98 ffff8800916cf6c0 ffff8800b65e1e98 0000000000000000 >> Call Trace: >> [<ffffffff816add89>] mutex_unlock+0x9/0x10 >> [<ffffffff8110ec70>] vfs_rmdir+0xb0/0x100 >> [<ffffffff8110ed96>] do_rmdir+0xd6/0x130 >> [<ffffffff81102063>] ? fput+0x1c3/0x260 >> [<ffffffff810fe648>] ? filp_close+0x68/0xa0 >> [<ffffffff8110ee41>] sys_rmdir+0x11/0x20 >> [<ffffffff816b6f3b>] system_call_fastpath+0x16/0x1b >> Code: 75 1b 65 48 8b 04 25 c8 b5 00 00 48 63 80 44 e0 ff ff a9 00 ff ff 07 0f 85 bb 00 00 00 9c 41 5e fa b8 00 01 00 00 4d 8d 6c 24 04 <f0> 66 41 0f c1 45 00 38 e0 74 08 f3 90 41 8a 45 00 eb f4 44 8b >> RIP [<ffffffff816adc93>] __mutex_unlock_slowpath+0x53/0x140 >> RSP <ffff8800b65e1e28> >> CR2: 00000000000000a4 >> ---[ end trace f515ec8376bdb799 ]--- >> >> How can I further debug this? At this point, it seems to be happening several times daily. > > Fabio reported a similar bug, > 3.0.3 [BUG] unable to handle kernel NULL pointer dereference > http://marc.info/?t=131416920900001&r=1&w=2 > > Do you have a test case to trigger this bug reliably? Unfortunatey not, so far. This problem happens on a quite loaded server with apache on it and it is difficult to find root cause or at least a situation able to trigger it. Still digging, but I wouldn't expect to find something useful in short time. -- Fabio -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
