[Bugme-new] [Bug 33932] New: Oops in cfq_unlink_blkio_group on cgroup rmdir

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=33932

           Summary: Oops in cfq_unlink_blkio_group on cgroup rmdir
           Product: IO/Storage
           Version: 2.5
    Kernel Version: 2.6.38.2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Block Layer
        AssignedTo: axboe at kernel.dk
        ReportedBy: cbay at excellency.fr
        Regression: No


I have a Python script that removes all empty cgroups every day, one at a time.
It's run fine for 3 weeks, but yesterday I got this oops:

[1921483.650066] BUG: unable to handle kernel NULL pointer dereference at      
    (null)
[1921483.650215] IP: [<ffffffff8149a5a6>] _raw_spin_lock_irqsave+0x16/0x30
[1921483.650270] PGD 1c8b7067 PUD 659a9067 PMD 0 
[1921483.650321] Oops: 0002 [#1] SMP 
[1921483.650367] last sysfs file: /sys/module/drbd/parameters/cn_idx
[1921483.650417] CPU 5 
[1921483.650422] Modules linked in: nf_conntrack_ftp xt_owner xt_NFLOG
nfnetlink_log nfnetlink nf_conntrack_ipv6 nf_defrag_ipv6 xt_recent
nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack xt_multiport drbd
lru_cache ehci_hcd usbcore netconsole e1000e [last unloaded: nf_conntrack_ftp]
[1921483.650693] 
[1921483.650728] Pid: 1945882, comm: python Not tainted 2.6.38.2 #1 Supermicro
H8SCM/H8SCM
[1921483.650827] RIP: 0010:[<ffffffff8149a5a6>]  [<ffffffff8149a5a6>]
_raw_spin_lock_irqsave+0x16/0x30
[1921483.650915] RSP: 0018:ffff8800a38bde10  EFLAGS: 00010046
[1921483.650962] RAX: 0000000000000246 RBX: ffff88010b420030 RCX:
0000000000000246
[1921483.651041] RDX: 0000000000000100 RSI: ffff88010b420030 RDI:
0000000000000000
[1921483.651120] RBP: ffff88010b420030 R08: 0000000000000009 R09:
ffff880020ca4558
[1921483.651199] R10: ffff880020ca4438 R11: ffff880020ca44f8 R12:
ffff88040de34c00
[1921483.651278] R13: ffff88040de34c00 R14: ffff8803beec0d80 R15:
0000000000d18530
[1921483.651357] FS:  00007f7fda5ff6e0(0000) GS:ffff8800dfd40000(0000)
knlGS:00000000f731f6d0
[1921483.651439] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[1921483.651489] CR2: 0000000000000000 CR3: 000000007e32e000 CR4:
00000000000006e0
[1921483.651568] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[1921483.651647] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[1921483.651726] Process python (pid: 1945882, threadinfo ffff8800a38bc000,
task ffff88001abe3340)
[1921483.651809] Stack:
[1921483.651845]  ffffffff81249a69 ffffffff81864ba0 ffff88010b420030
ffff8803beec0da4
[1921483.651934]  ffffffff81246aae ffffffff81863a00 ffff88022637e400
ffff8800020b6d00
[1921483.652022]  ffff88003b1c6b9c ffff88040fb31d1c ffffffff81088679
ffff88003b1c6b40
[1921483.652111] Call Trace:
[1921483.652152]  [<ffffffff81249a69>] ? cfq_unlink_blkio_group+0x19/0x90
[1921483.652205]  [<ffffffff81246aae>] ? blkiocg_destroy+0x9e/0x140
[1921483.652256]  [<ffffffff81088679>] ? cgroup_diput+0x69/0x100
[1921483.652306]  [<ffffffff810fb9c9>] ? dput+0x1d9/0x320
[1921483.652354]  [<ffffffff810f3f90>] ? do_rmdir+0x100/0x130
[1921483.652406]  [<ffffffff810c7d2a>] ? sys_munmap+0x5a/0x80
[1921483.652455]  [<ffffffff8100ae92>] ? system_call_fastpath+0x16/0x1b
[1921483.652505] Code: e0 74 06 f3 90 8a 07 eb f6 c3 66 66 2e 0f 1f 84 00 00 00
00 00 9c 58 66 66 90 66 90 48 89 c1 fa 66 66 90 66 66 90 ba 00 01 00 00 <f0> 66
0f c1 17 38 f2 74 06 f3 90 8a 17 eb f6 48 89 c8 c3 0f 1f 
[1921483.652813] RIP  [<ffffffff8149a5a6>] _raw_spin_lock_irqsave+0x16/0x30
[1921483.652866]  RSP <ffff8800a38bde10>
[1921483.652907] CR2: 0000000000000000
[1921483.653321] ---[ end trace d9216500967642d6 ]---

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