This is a note to let you know that I've just added the patch titled
md: fix a race condition for flush request handling
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-fix-a-race-condition-for-flush-request-handling.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 79bf31a3b2a7ca467cfec8ff97d359a77065d01f Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli@xxxxxx>
Date: Thu, 21 Sep 2017 09:55:28 -0700
Subject: md: fix a race condition for flush request handling
From: Shaohua Li <shli@xxxxxx>
commit 79bf31a3b2a7ca467cfec8ff97d359a77065d01f upstream.
md_submit_flush_data calls pers->make_request, which missed the suspend check.
Fix it with the new md_handle_request API.
Reported-by: Nate Dailey <nate.dailey@xxxxxxxxxxx>
Tested-by: Nate Dailey <nate.dailey@xxxxxxxxxxx>
Fix: cc27b0c78c79(md: fix deadlock between mddev_suspend() and md_write_start())
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -439,16 +439,22 @@ static void md_submit_flush_data(struct
struct mddev *mddev = container_of(ws, struct mddev, flush_work);
struct bio *bio = mddev->flush_bio;
+ /*
+ * must reset flush_bio before calling into md_handle_request to avoid a
+ * deadlock, because other bios passed md_handle_request suspend check
+ * could wait for this and below md_handle_request could wait for those
+ * bios because of suspend check
+ */
+ mddev->flush_bio = NULL;
+ wake_up(&mddev->sb_wait);
+
if (bio->bi_iter.bi_size == 0)
/* an empty barrier - all done */
bio_endio(bio);
else {
bio->bi_opf &= ~REQ_PREFLUSH;
- mddev->pers->make_request(mddev, bio);
+ md_handle_request(mddev, bio);
}
-
- mddev->flush_bio = NULL;
- wake_up(&mddev->sb_wait);
}
void md_flush_request(struct mddev *mddev, struct bio *bio)
Patches currently in stable-queue which might be from shli@xxxxxx are
queue-4.13/md-separate-request-handling.patch
queue-4.13/md-raid5-preserve-stripe_on_unplug_list-in-break_stripe_batch_list.patch
queue-4.13/md-fix-a-race-condition-for-flush-request-handling.patch
queue-4.13/md-raid5-fix-a-race-condition-in-stripe-batch.patch