[Linux-cachefs] Kernel traceback on 3.10.10

[Mark Moseley]

Was testing out fscache for the first time in a while. On a fairly busy
box, I got this after about an hour of traffic. OS is Ubuntu Precise
64-bit, on a Dell Poweredge 420. The cache is on a 500gb SATA drive:

/dev/sdb1      480590564  5927608 450227244   2% /var/cache/fscache


kernel: [ 3962.680184] BUG: unable to handle kernel NULL pointer
dereference at 0000000000000010
kernel: [ 3962.688990] IP: [<ffffffff812910c3>]
__fscache_uncache_page+0x23/0x160
kernel: [ 3962.696319] PGD 0
kernel: [ 3962.698584] Thread overran stack, or stack corrupted
kernel: [ 3962.704140] Oops: 0000 [#1] SMP
kernel: [ 3962.707782] Modules linked in: dell_rbu aesni_intel microcode
sb_edac wmi edac_core hid_generic usbhid hid
kernel: [ 3962.718724] CPU: 5 PID: 32383 Comm: php Not tainted 3.10.10 #1
kernel: [ 3962.725249] Hardware name: Dell Inc. PowerEdge R420/072XWF, BIOS
1.3.5 08/21/2012
kernel: [ 3962.753557] task: ffff8801f1004890 ti: ffff8801f1004e10 task.ti:
ffff8801f1004e10
kernel: [ 3962.761931] RIP: 0010:[<ffffffff812910c3>]  [<ffffffff812910c3>]
__fscache_uncache_page+0x23/0x160
kernel: [ 3962.771973] RSP: 0018:ffff88003e3ef8c8  EFLAGS: 00210282
kernel: [ 3962.777917] RAX: 0000000000000000 RBX: ffff8800b7037438 RCX:
ffff88022ffc75e8
kernel: [ 3962.785903] RDX: 000000000000014e RSI: ffffea000ee5eb00 RDI:
ffff8800b7037438
kernel: [ 3962.793889] RBP: ffff88003e3ef8e8 R08: 0000000000000001 R09:
0000000000000005
kernel: [ 3962.801893] R10: 0000000000000000 R11: 0000000000000000 R12:
ffffea000ee5eb00
kernel: [ 3962.809895] R13: ffff8804190477d8 R14: 0000000000000000 R15:
0000000000000000
kernel: [ 3962.817892] FS:  0000000000000000(0000)
GS:ffff88042fc40000(0063) knlGS:00000000e347c700
kernel: [ 3962.826985] CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
kernel: [ 3962.833434] CR2: 0000000000000010 CR3: 0000000001d6c000 CR4:
00000000000607f0
kernel: [ 3962.841438] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
kernel: [ 3962.849444] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
kernel: [ 3962.857448] Stack:
kernel: [ 3962.859711]  ffffea000ee5eb00 ffffea000ee5eb00 ffff8800b7037438
ffff8804190477d8
kernel: [ 3962.868086]  ffff88003e3ef908 ffffffff81353522 ffffea000ee5eb00
0000000000000000
kernel: [ 3962.876460]  ffff88003e3ef928 ffffffff81342ca0 ffffea000ee5eb00
ffff8804190477d8
kernel: [ 3962.884832] Call Trace:
kernel: [ 3962.887598]  [<ffffffff81353522>]
__nfs_fscache_invalidate_page+0x42/0x70
kernel: [ 3962.895216]  [<ffffffff81342ca0>] nfs_invalidate_page+0x60/0x80
kernel: [ 3962.901863]  [<ffffffff811aaf99>] truncate_inode_page+0x89/0x90
kernel: [ 3962.908507]  [<ffffffff811ab102>]
truncate_inode_pages_range+0x162/0x4b0
kernel: [ 3962.916030]  [<ffffffff81d44869>] ? mutex_unlock+0x19/0x20
kernel: [ 3962.922191]  [<ffffffff811c4a88>] ?
unmap_mapping_range+0x98/0x180
kernel: [ 3962.929128]  [<ffffffff811ab4fd>] truncate_inode_pages+0x2d/0x40
kernel: [ 3962.955657]  [<ffffffff811ab55f>] truncate_pagecache+0x4f/0x70
kernel: [ 3962.962206]  [<ffffffff81344080>]
nfs_setattr_update_inode+0xa0/0x120
kernel: [ 3962.969433]  [<ffffffff813568b4>] nfs3_proc_setattr+0xc4/0xe0
kernel: [ 3962.975883]  [<ffffffff813457bf>] nfs_setattr+0xcf/0x170
kernel: [ 3962.981848]  [<ffffffff8121d5bb>] notify_change+0x1cb/0x390
kernel: [ 3962.988107]  [<ffffffff811fa73b>] do_truncate+0x7b/0xc0
kernel: [ 3962.993975]  [<ffffffff8120f63f>] do_last+0x6bf/0x1110
kernel: [ 3962.999746]  [<ffffffff8120bc12>] ? link_path_walk+0x242/0x930
kernel: [ 3963.006283]  [<ffffffff81210151>] path_openat+0xc1/0x4d0
kernel: [ 3963.012247]  [<ffffffff812109cd>] do_filp_open+0x4d/0xb0
kernel: [ 3963.018211]  [<ffffffff811fbb74>] do_sys_open+0x104/0x250
kernel: [ 3963.024275]  [<ffffffff8125a016>] compat_SyS_open+0x36/0x50
kernel: [ 3963.030531]  [<ffffffff81d5272c>] sysenter_dispatch+0x7/0x24
kernel: [ 3963.036969] Code: ff eb a7 0f 1f 44 00 00 66 66 66 66 90 55 48
89 e5 48 83 ec 20 48 89 5d e8 48 89 fb 4c 89 65 f0 4c 89 6d f8 49 89 f4 48
8b 43 40 <80> 78 10 00 0f 84 c0 00 00 00 4d 85 e4 0f 84 ed 00 00 00 f0 ff
kernel: [ 3963.059163] RIP  [<ffffffff812910c3>]
__fscache_uncache_page+0x23/0x160
kernel: [ 3963.066599]  RSP <ffff88003e3ef8c8>
kernel: [ 3963.070521] CR2: 0000000000000010
kernel: [ 3963.075102] ---[ end trace 454db2fd8476c38c ]---