Messages in this thread | | | Date | Fri, 25 Apr 2008 19:21:53 +0200 | From | Eric Dumazet <> | Subject | Re: BUG in strnlen |
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Randy Dunlap a écrit : > Hi, > > All of my daily testing (x86_64, 4 CPUs, 8 GB RAM) > since (after) 2.6.25 is seeing this BUG: > (i.e., 2.6.25 does not do this) > > > BUG: unable to handle kernel paging request at ffffffffa00b7551 > IP: [<ffffffff80357aac>] strnlen+0x15/0x1f > PGD 203067 PUD 207063 PMD 27e44f067 PTE 0 > Oops: 0000 [1] SMP > CPU 3 > Modules linked in: hp_ilo parport_pc lp parport tg3 cciss ehci_hcd ohci_hcd uhci_hcd [last unloaded: reiserfs] > Pid: 20926, comm: cat Not tainted 2.6.25-git5 #1 > RIP: 0010:[<ffffffff80357aac>] [<ffffffff80357aac>] strnlen+0x15/0x1f > RSP: 0018:ffff810274981cc8 EFLAGS: 00010297 > RAX: ffffffffa00b7551 RBX: ffff810274981d38 RCX: ffffffff80603719 > RDX: ffff810274981d68 RSI: fffffffffffffffe RDI: ffffffffa00b7551 > RBP: ffff810274981cc8 R08: 00000000ffffffff R09: 00000000000000c8 > R10: 0000000000000050 R11: 0000000000000246 R12: ffff8102364600cc > R13: ffffffffa00b7551 R14: 0000000000000011 R15: 0000000000000010 > FS: 00007f956375d6f0(0000) GS:ffff81027f808980(0000) knlGS:00000000f7f7f6c0 > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > CR2: ffffffffa00b7551 CR3: 00000002734d5000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process cat (pid: 20926, threadinfo ffff810274980000, task ffff81026d18ce20) > Stack: ffff810274981d28 ffffffff80358d5a ffff810274981d28 0000000000000f34 > ffff8102364600cc ffff810236461000 ffffffff80603719 ffff81024ac14f00 > ffff81024ac14f00 0000000000000004 0000000000000000 0000000000000000 > Call Trace: > [<ffffffff80358d5a>] vsnprintf+0x31b/0x592 > [<ffffffff802a78eb>] seq_printf+0x7e/0xa7 > [<ffffffff8024c6fe>] ? debug_mutex_free_waiter+0x46/0x4a > [<ffffffff8053aaa2>] ? __down_read+0x17/0x92 > [<ffffffff80539c25>] ? __mutex_lock_slowpath+0x1d8/0x1e5 > [<ffffffff802886c2>] ? count_partial+0x45/0x4d > [<ffffffff80289a6d>] s_show+0x7e/0xcb > [<ffffffff802a7dd9>] seq_read+0x10b/0x298 > [<ffffffff802c7dbb>] proc_reg_read+0x7b/0x95 > [<ffffffff8028ec0b>] vfs_read+0xab/0x154 > [<ffffffff8028f015>] sys_read+0x47/0x6f > [<ffffffff8020c182>] tracesys+0xd5/0xda > > > Code: 48 8d 44 11 ff 40 38 30 74 0a 48 ff c8 48 39 d0 73 f3 31 c0 c9 c3 55 48 89 f8 48 89 e5 eb 03 48 ff c0 48 ff ce 48 83 fe ff 74 05 <80> 38 00 75 ef c9 48 29 f8 c3 55 31 c0 48 89 e5 eb 13 41 38 c8 > RIP [<ffffffff80357aac>] strnlen+0x15/0x1f > RSP <ffff810274981cc8> > CR2: ffffffffa00b7551 > > > --- > > My initial thoughts are :
Fault address is 0xffffffffa00b7551 which is in module mapping space on x86_64
strnlen() is OK
Some module created a kmem_cache (with kmem_cache_create()). slub or slab kept a pointer to the cache name in their internal structures. Module was unloaded but forgot to destroy kmem cache before unloading.
Fault happens while doing "cat /proc/slabinfo", when trying to dereference cache name since module was unloaded and its memory unmapped.
Next step is to find which module was unloaded ...
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