[Xen-bugs] [Bug 1469] New: Spinlock assertion copying large files as root

[bugzilla-daemon@xxxxxxxxxxxxxxxxxxx]

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1469

           Summary: Spinlock assertion copying large files as root
           Product: Xen
           Version: unstable
          Platform: x86-64
               URL: http://www.oggfrog.com/bug-reports/xen/
        OS/Version: Linux-2.6
            Status: NEW
          Severity: critical
          Priority: P2
         Component: Guest-OS
        AssignedTo: xen-bugs@xxxxxxxxxxxxxxxxxxx
        ReportedBy: mdc@xxxxxxxxx


Using the xen-tip/next Linux kernel from May 22, 2009, I get the following
errors whenever I try to copy a large file as root.

Copying small files as root works OK, as does copying any file as a regular
user.

I don't know if it matters, but the large files I have experienced this with
are sparse files, created to be file-backed Xen VBDs.

I don't know where the cutoff lies between small files that don't experience
the bug and large files that do, but I could find out if you need me to.


winxp.img dentry_open failed
BUG: using smp_processor_id() in preemptible [00000000] code: cp/6492
caller is trace_hw_branch_oops+0x15/0x68
Pid: 6492, comm: cp Tainted: G        W  2.6.30-rc6-tip #1
Call Trace:
 [<ffffffff811e726c>] debug_smp_processor_id+0xd0/0xe8
 [<ffffffff810c1ff1>] trace_hw_branch_oops+0x15/0x68
 [<ffffffff813fb064>] oops_begin+0x12/0x90
 [<ffffffff8110ac44>] ? fput+0x1c/0x1f
 [<ffffffff8106c835>] ? search_exception_tables+0x37/0x3e
 [<ffffffff8100ec89>] ? xen_force_evtchn_callback+0xd/0xf
 [<ffffffff810381ee>] no_context+0xbd/0x14a
 [<ffffffff8100ec89>] ? xen_force_evtchn_callback+0xd/0xf
 [<ffffffff81038426>] __bad_area_nosemaphore+0x1ab/0x1d1
 [<ffffffff8100f4d2>] ? check_events+0x12/0x20
 [<ffffffff813fc706>] ? do_page_fault+0x134/0x281
 [<ffffffff813f96fa>] ? _spin_unlock_irqrestore+0x4b/0x87
 [<ffffffff811d4d72>] ? __up_read+0x7c/0x85
 [<ffffffff8100f4bf>] ? xen_restore_fl_direct_end+0x0/0x1
 [<ffffffff813f9728>] ? _spin_unlock_irqrestore+0x79/0x87
 [<ffffffff811d4d72>] ? __up_read+0x7c/0x85
 [<ffffffff810384a8>] bad_area+0x47/0x50
 [<ffffffff813fc706>] ? do_page_fault+0x134/0x281
 [<ffffffff813fc7a4>] do_page_fault+0x1d2/0x281
 [<ffffffff813fa3b5>] page_fault+0x25/0x30
 [<ffffffff8110ac35>] ? fput+0xd/0x1f
 [<ffffffff813f7e90>] ? mutex_unlock+0xe/0x10
 [<ffffffff811afcf8>] ima_path_check+0x1bb/0x1dc
 [<ffffffff81113f64>] may_open+0xc5/0x1e0
 [<ffffffff811147b8>] do_filp_open+0x470/0x8c2
 [<ffffffff8100fea2>] ? xen_spin_unlock+0x11/0x2e
 [<ffffffff8100f4bf>] ? xen_restore_fl_direct_end+0x0/0x1
 [<ffffffff811e6e82>] ? _raw_spin_unlock+0x8f/0x96
 [<ffffffff8111e8a8>] ? alloc_fd+0x122/0x133
 [<ffffffff81107c39>] do_sys_open+0x5b/0xdb
 [<ffffffff81107cec>] sys_open+0x20/0x22
 [<ffffffff81012eb2>] system_call_fastpath+0x16/0x1b
BUG: unable to handle kernel NULL pointer dereference at 000000000000001d
IP: [<ffffffff8110ac35>] fput+0xd/0x1f
PGD a48d1067 PUD ba6a9067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP 
last sysfs file: /sys/devices/system/cpu/cpu3/cache/index2/shared_cpu_map
CPU 0 
Modules linked in: fuse iptable_nat nf_nat sco bridge stp bnep l2cap bluetooth
sunrpc ip6table_filter ip6_tables ipv6 ext2 dm_multipath uinput
snd_hda_codec_atihdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec
snd_hwdep snd_seq_dummy snd_seq_oss ppdev snd_seq_midi_event ohci1394 snd_seq
i2c_i801 ieee1394 i2c_core pcspkr iTCO_wdt iTCO_vendor_support serio_raw
snd_seq_device snd_pcm_oss igb snd_mixer_oss snd_pcm dca i5k_amb hwmon
snd_timer parport_pc snd parport floppy soundcore snd_page_alloc shpchp 3w_9xxx
[last unloaded: microcode]
Pid: 6492, comm: cp Tainted: G        W  2.6.30-rc6-tip #1 X7DWA
RIP: e030:[<ffffffff8110ac35>]  [<ffffffff8110ac35>] fput+0xd/0x1f
RSP: e02b:ffff880069993d88  EFLAGS: 00010282
RAX: 000000000000001d RBX: ffff8800a60299b0 RCX: 000000002c69b401
RDX: ffff8800bf025900 RSI: 0000000000000003 RDI: ffffffffffffffb5
RBP: ffff880069993d88 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000013ea9 R11: 000000000000003c R12: ffff8800bf0259e0
R13: ffffffffffffffb5 R14: ffff880069993e48 R15: ffff8800bf025900
FS:  00007f21759c5790(0000) GS:ffffc90000000000(0000) knlGS:0000000000000000
CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 000000000000001d CR3: 00000000ae8e0000 CR4: 0000000000002660
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process cp (pid: 6492, threadinfo ffff880069992000, task ffff8800a1580000)
Stack:
 ffff880069993dc8 ffffffff811afcf8 ffff8800a60299d8 ffff8800a1c4a760
 0000000000008001 0000000000000004 ffff880069993e48 ffff8800bf025900
 ffff880069993e08 ffffffff81113f64 ffff880069993e08 0000000000000000
Call Trace:
 [<ffffffff811afcf8>] ima_path_check+0x1bb/0x1dc
 [<ffffffff81113f64>] may_open+0xc5/0x1e0
 [<ffffffff811147b8>] do_filp_open+0x470/0x8c2
 [<ffffffff8100fea2>] ? xen_spin_unlock+0x11/0x2e
 [<ffffffff8100f4bf>] ? xen_restore_fl_direct_end+0x0/0x1
 [<ffffffff811e6e82>] ? _raw_spin_unlock+0x8f/0x96
 [<ffffffff8111e8a8>] ? alloc_fd+0x122/0x133
 [<ffffffff81107c39>] do_sys_open+0x5b/0xdb
 [<ffffffff81107cec>] sys_open+0x20/0x22
 [<ffffffff81012eb2>] system_call_fastpath+0x16/0x1b
Code: c7 87 cc 00 00 00 00 00 00 00 4c 89 ff e8 25 58 01 00 5b 5b 41 5c 41 5d
41 5e 41 5f c9 c3 55 48 89 e5 0f 1f 44 00 00 48 8d 47 68 <f0> 48 ff 08 0f 94 c2
84 d2 74 05 e8 45 fe ff ff c9 c3 55 48 89 
RIP  [<ffffffff8110ac35>] fput+0xd/0x1f
 RSP <ffff880069993d88>
CR2: 000000000000001d
---[ end trace 659513871364bdc7 ]---


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