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Commit 4b197769 authored by Mark Lord's avatar Mark Lord Committed by Jens Axboe
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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: default avatarMark Lord <mlord@pobox.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 749ef9f8

block/blk-exec.c

+8 −1
Original line number Diff line number Diff line
@@ -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
@@ -95,6 +96,12 @@ 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);



	/* 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)