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md/raid1,raid10: fix deadlock in read error recovery path

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raid1d and raid10d may resubmit a split md cloned bio while handling
a read error. In this case, resubmitting the bio can lead to a deadlock
if the array is suspended before md_handle_request() acquires an
active_io reference via percpu_ref_tryget_live().

Since the cloned bio already holds an active_io reference,
trying to acquire another reference via percpu_ref_tryget_live()
can lead to a deadlock while the array is suspended.

Fix this by using percpu_ref_get() for md cloned bios.

Fixes: bb2a9acefa ("md/raid1: switch to use md_account_bio() for io accounting")
Fixes: 8204552383 ("md/raid10: switch to use md_account_bio() for io accounting")
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Reviewed-by: Xiao Ni <xiao@kernel.org>
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/20260501114652.590037-2-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai <yukuai@fygo.io>
This commit is contained in:
Abd-Alrhman Masalkhi
2026-05-01 13:46:49 +02:00
committed by Yu Kuai
parent 6b8a26af06
commit 7b15c24f80
2 changed files with 21 additions and 9 deletions
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25
drivers/md/md.c
View File

@@ -395,17 +395,24 @@ static bool is_suspended(struct mddev *mddev, struct bio *bio)
bool md_handle_request(struct mddev *mddev, struct bio *bio)
{
check_suspended:
if (is_suspended(mddev, bio)) {
/* Bail out if REQ_NOWAIT is set for the bio */
if (bio->bi_opf & REQ_NOWAIT) {
bio_wouldblock_error(bio);
return true;
if (unlikely(md_cloned_bio(mddev, bio))) {
/*
* This bio is an MD cloned bio and already holds an
* active_io reference, so percpu_ref_get() is safe here.
*/
percpu_ref_get(&mddev->active_io);
} else {
if (is_suspended(mddev, bio)) {
/* Bail out if REQ_NOWAIT is set for the bio */
if (bio->bi_opf & REQ_NOWAIT) {
bio_wouldblock_error(bio);
return true;
}
wait_event(mddev->sb_wait, !is_suspended(mddev, bio));
}
wait_event(mddev->sb_wait, !is_suspended(mddev, bio));
if (!percpu_ref_tryget_live(&mddev->active_io))
goto check_suspended;
}
if (!percpu_ref_tryget_live(&mddev->active_io))
goto check_suspended;
if (!mddev->pers->make_request(mddev, bio)) {
percpu_ref_put(&mddev->active_io);
if (mddev_is_dm(mddev) && mddev->pers->prepare_suspend)

5
drivers/md/md.h
View File

@@ -1044,6 +1044,11 @@ void mddev_update_io_opt(struct mddev *mddev, unsigned int nr_stripes);
extern const struct block_device_operations md_fops;
static inline bool md_cloned_bio(struct mddev *mddev, struct bio *bio)
{
return bio->bi_pool == &mddev->io_clone_set;
}
/*
* MD devices can be used undeneath by DM, in which case ->gendisk is NULL.
*/