[Lustre-discuss] [bug?] mdc_enter_request() problems
green at whamcloud.com
Mon Aug 8 11:20:52 PDT 2011
I guess this is some sort of 1.8 due to the init_waitq_head call.
2.1 code is notably different in this case after LU-234 landed, namely removing
mcw_entry from the list on error.
The patch originates from bug 18213 and claimed as 1.8 port to 2.1, but I don't see anything like this in the 1.8 patch.
On Aug 8, 2011, at 2:07 PM, Andreas Dilger wrote:
> On 2011-08-08, at 10:03 AM, chas williams - CONTRACTOR wrote:
>> we have seen a few crashes that look like:
>> [250696.381575] RIP: 0010:[<ffffffffa0a1f9e4>] [<ffffffffa0a1f9e4>] mdc_exit_request+0x74/0xb0 [mdc]
>> [250696.381575] Call Trace:
>> [250696.381575] [<ffffffffa0a25042>] mdc_intent_getattr_async_interpret+0x82/0x500 [mdc]
>> [250696.381575] [<ffffffffa089efd0>] ptlrpc_check_set+0x200/0x1690 [ptlrpc]
>> [250696.381575] [<ffffffffa08d3140>] ptlrpcd_check+0x110/0x250 [ptlrpc]
>> and i sort of gather the problem arises from mdc_enter_request().
>> it allocates an mdc_cache_waiter on the stack and inserts it into the
>> wait list and then returns.
>> int mdc_enter_request(struct client_obd *cli)
>> struct mdc_cache_waiter mcw;
>> list_add_tail(&mcw.mcw_entry, &cli->cl_cache_waiters);
>> later mdc_exit_request() finds this mcw by iterating the list.
>> seeing as mcw was allocated on the stack, i dont think you can do this.
>> mcw might have been reused by the time mdc_exit_request() gets around
>> to removing it.
> What version of Lustre is this?
> Cheers, Andreas
> Andreas Dilger
> Principal Engineer
> Whamcloud, Inc.
Senior Software Engineer
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