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authorMing Lei <ming.lei@redhat.com>2020-03-18 06:43:36 +0300
committerJens Axboe <axboe@kernel.dk>2020-03-18 17:48:03 +0300
commitde6a78b601c529398ad1448e3bffcade1fcf5a70 (patch)
tree5568090a7bd5dedc3b76fd181bbd6fd99abff17d
parentd981cb5b9fa0da9da6a6c8b9ae7cbe789c3b3214 (diff)
downloadlinux-de6a78b601c529398ad1448e3bffcade1fcf5a70.tar.xz
block: Prevent hung_check firing during long sync IO
submit_bio_wait() can be called from ioctl(BLKSECDISCARD), which may take long time to complete, as Salman mentioned, 4K BLKSECDISCARD takes up to 100 second on some devices. Also any block I/O operation that occurs after the BLKSECDISCARD is submitted will also potentially be affected by the hung task timeouts. Another report is that task hang can be observed when running mkfs over raid10 which takes a small max discard sectors limit because of chunk size. So prevent hung_check from firing by taking same approach used in blk_execute_rq(), and the wake-up interval is set as half the hung_check timer period, which keeps overhead low enough. Cc: Salman Qazi <sqazi@google.com> Cc: Jesse Barnes <jsbarnes@google.com> Cc: Bart Van Assche <bvanassche@acm.org> Link: https://lkml.org/lkml/2020/2/12/1193 Reported-by: Salman Qazi <sqazi@google.com> Reviewed-by: Jesse Barnes <jsbarnes@google.com> Reviewed-by: Salman Qazi <sqazi@google.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/bio.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/block/bio.c b/block/bio.c
index 94d697217887..0985f3422556 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -17,6 +17,7 @@
#include <linux/cgroup.h>
#include <linux/blk-cgroup.h>
#include <linux/highmem.h>
+#include <linux/sched/sysctl.h>
#include <trace/events/block.h>
#include "blk.h"
@@ -1019,12 +1020,21 @@ static void submit_bio_wait_endio(struct bio *bio)
int submit_bio_wait(struct bio *bio)
{
DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map);
+ unsigned long hang_check;
bio->bi_private = &done;
bio->bi_end_io = submit_bio_wait_endio;
bio->bi_opf |= REQ_SYNC;
submit_bio(bio);
- wait_for_completion_io(&done);
+
+ /* 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_io_timeout(&done,
+ hang_check * (HZ/2)))
+ ;
+ else
+ wait_for_completion_io(&done);
return blk_status_to_errno(bio->bi_status);
}