From 4b1977698ceb4c4caa800d475127139da49966f9 Mon Sep 17 00:00:00 2001 From: Mark Lord Date: Fri, 24 Sep 2010 09:51:13 -0400 Subject: block: Prevent hang_check firing during long I/O During long I/O operations, the hang_check timer may fire, trigger stack dumps that unnecessarily alarm the user. Eg. hdparm --security-erase NULL /dev/sdb ## can take *hours* to complete So, if hang_check is armed, we should wake up periodically to prevent it from triggering. This patch uses a wake-up interval equal to half the hang_check timer period, which keeps overhead low enough. Signed-off-by: Mark Lord Signed-off-by: Jens Axboe --- block/blk-exec.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/blk-exec.c b/block/blk-exec.c index e1672f14840e..cf1456a02acd 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -80,6 +80,7 @@ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk, DECLARE_COMPLETION_ONSTACK(wait); char sense[SCSI_SENSE_BUFFERSIZE]; int err = 0; + unsigned long hang_check; /* * we need an extra reference to the request, so we can look at @@ -95,7 +96,13 @@ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk, rq->end_io_data = &wait; blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); - wait_for_completion(&wait); + + /* Prevent hang_check timer from firing at us during very long I/O */ + hang_check = sysctl_hung_task_timeout_secs; + if (hang_check) + while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2))); + else + wait_for_completion(&wait); if (rq->errors) err = -EIO; -- cgit v1.2.3-58-ga151