lkml.org 
[lkml]   [2011]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
DateFri, 25 Mar 2011 16:22:28 +0100
FromMarkus Trippelsdorf <>
SubjectRe: [OOPS] elevator private data for REQ_FLUSH
On 2011.03.25 at 17:15 +0200, Sergey Senozhatsky wrote:
> Hello,
>
> Commit
> 9d5a4e946ce5352f19400b6370f4cd8e72806278
> block: skip elevator data initialization for flush requests
>
> Skip elevator initialization for flush requests by passing priv=0 to
> blk_alloc_request() in get_request(). As such elv_set_request() is
> never called for flush requests.
>
> introduced priv flag, to skip elevator_private data init for FLUSH requests.
> This, I guess, lead to NULL pointer deref on my machine in cfq_insert_request,
> which requires elevator_private to be set:
>
> 1 [ 78.982169] Call Trace:
> 2 [ 78.982178] [<ffffffff8122d1fe>] cfq_insert_request+0x4e/0x47d
> 3 [ 78.982184] [<ffffffff8123e139>] ? do_raw_spin_lock+0x6b/0x122

> Should we in that case use ELEVATOR_INSERT_FLUSH for REQ_FLUSH | REQ_FUA requests
> (like below)?
>
> ---
>
> block/elevator.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/block/elevator.c b/block/elevator.c
> index c387d31..b17e577 100644
> --- a/block/elevator.c
> +++ b/block/elevator.c
> @@ -734,6 +734,8 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
> q->end_sector = rq_end_sector(rq);
> q->boundary_rq = rq;
> }
> + } else if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
> + where = ELEVATOR_INSERT_FLUSH;
> } else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
> where == ELEVATOR_INSERT_SORT)
> where = ELEVATOR_INSERT_BACK;

Thanks. That solves all (corruption-) problems that I reported earlier in an other
thread.
--
Markus


\
 
 \ /
  Last update: 2011-03-25 16:25    [from the cache]
©2003-2010