Re: oops in close when exiting fsx

From: Steve French
Date: Sun Aug 13 2006 - 14:41:35 EST


Chuck Ebbert wrote:
In-Reply-To: <44DE2EA6.4060809@xxxxxxxxxxxxx>

On Sat, 12 Aug 2006 14:40:22 -0500, Steve French wrote:

ctl-c exiting fsx after a few hours with 2.6.18-rc4 got the following oops - anyone recognize it?
Although I didn't see cifs symbols on the call stack it is running on a cifs mount, but it is not
one I have seen before.

EIP is at __down+0x56/0xc5

1a: 8d 43 08 lea 0x8(%ebx),%eax <= addr of sema wait queue list_head
1d: 8b 48 04 mov 0x4(%eax),%ecx <= list->prev
20: 8d 54 24 2c lea 0x2c(%esp),%edx
24: 89 50 04 mov %edx,0x4(%eax)
27: 89 44 24 2c mov %eax,0x2c(%esp)
0: 89 11 mov %edx,(%ecx) <===== list->prev->next = new

The semaphore's wait queue head is corrupted: 'prev' is 0.

[<c1038908>] mempool_free+0x43/0x46
[<c1013678>] default_wake_function+0x0/0xc
[<c132ed37>] __down_failed+0x7/0xc
[<fa2da685>] .text.lock.file+0x87/0x9a [cifs] <=====
[<c104e807>] __fput+0xab/0x148
[<c104c453>] filp_close+0x4e/0x54
[<c101773a>] put_files_struct+0x64/0xa6
[<c1018581>] do_exit+0x1c7/0x675
[<c10052b0>] do_syscall_trace+0x12b/0x172
[<c1018a8b>] sys_exit_group+0x0/0xd
[<c1002abf>] syscall_call+0x7/0xb

It came from a lock section in the cifs code. If you disassemble
.text.lock.file in cifs.o, at offset 0x87 (or shortly after) you
will see a jump back to the code that's trying to get the semaphore.



Thanks - This is a part of new cifs code recently added to handle posix locks (it has not pushed to mainline yet) better

down(&pSMBFile->lock_sem);
list_for_each_entry_safe(li, tmp, &pSMBFile->llist, llist) {
list_del(&li->llist);
kfree(li);
}
up(&pSMBFile->lock_sem);


My guess is that there is a path in which the lock_sem is not initialized - will trace that.
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