* [PATCH] 2.6.13-rc1 get_request nastiness
@ 2005-06-29 14:15 Hugh Dickins
2005-06-29 17:58 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Hugh Dickins @ 2005-06-29 14:15 UTC (permalink / raw)
To: Linus Torvalds; +Cc: Andrew Morton, Jens Axboe, linux-kernel
get_request is now expected to be holding on to queue_lock, with interrupts
disabled, when it returns NULL; but one path forgot that, causing all kinds
of nastiness under swap load - badness backtraces, strange failures, BUGs.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
--- 2.6.13-rc1/drivers/block/ll_rw_blk.c 2005-06-29 11:54:08.000000000 +0100
+++ linux/drivers/block/ll_rw_blk.c 2005-06-29 14:41:04.000000000 +0100
@@ -1917,10 +1917,9 @@ get_rq:
* limit of requests, otherwise we could have thousands of requests
* allocated with any setting of ->nr_requests
*/
- if (rl->count[rw] >= (3 * q->nr_requests / 2)) {
- spin_unlock_irq(q->queue_lock);
+ if (rl->count[rw] >= (3 * q->nr_requests / 2))
goto out;
- }
+
rl->count[rw]++;
rl->starved[rw] = 0;
if (rl->count[rw] >= queue_congestion_on_threshold(q))
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH] 2.6.13-rc1 get_request nastiness
2005-06-29 14:15 [PATCH] 2.6.13-rc1 get_request nastiness Hugh Dickins
@ 2005-06-29 17:58 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2005-06-29 17:58 UTC (permalink / raw)
To: Hugh Dickins; +Cc: Linus Torvalds, Andrew Morton, linux-kernel
On Wed, Jun 29 2005, Hugh Dickins wrote:
> get_request is now expected to be holding on to queue_lock, with interrupts
> disabled, when it returns NULL; but one path forgot that, causing all kinds
> of nastiness under swap load - badness backtraces, strange failures, BUGs.
>
> Signed-off-by: Hugh Dickins <hugh@veritas.com>
>
> --- 2.6.13-rc1/drivers/block/ll_rw_blk.c 2005-06-29 11:54:08.000000000 +0100
> +++ linux/drivers/block/ll_rw_blk.c 2005-06-29 14:41:04.000000000 +0100
> @@ -1917,10 +1917,9 @@ get_rq:
> * limit of requests, otherwise we could have thousands of requests
> * allocated with any setting of ->nr_requests
> */
> - if (rl->count[rw] >= (3 * q->nr_requests / 2)) {
> - spin_unlock_irq(q->queue_lock);
> + if (rl->count[rw] >= (3 * q->nr_requests / 2))
> goto out;
> - }
> +
Woops, my bad, sorry about that. I still have to think about that
locking, not directly obvious. Thanks Hugh!
--
Jens Axboe
^ permalink raw reply [flat|nested] 2+ messages in thread
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