[3.11.y.z extended stable] Patch "block: add cond_resched() to potentially long running ioctl discard" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Fri Feb 21 12:25:21 UTC 2014
This is a note to let you know that I have just added a patch titled
block: add cond_resched() to potentially long running ioctl discard
to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 46d61c4a64caeb15b2ead199eae89af54ee38524 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe at fb.com>
Date: Wed, 12 Feb 2014 09:34:01 -0700
Subject: block: add cond_resched() to potentially long running ioctl discard
loop
commit c8123f8c9cb517403b51aa41c3c46ff5e10b2c17 upstream.
When mkfs issues a full device discard and the device only
supports discards of a smallish size, we can loop in
blkdev_issue_discard() for a long time. If preempt isn't enabled,
this can turn into a softlock situation and the kernel will
start complaining.
Add an explicit cond_resched() at the end of the loop to avoid
that.
Signed-off-by: Jens Axboe <axboe at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
block/blk-lib.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index d6f50d5..9a32f58 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -121,6 +121,14 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
atomic_inc(&bb.done);
submit_bio(type, bio);
+
+ /*
+ * We can loop for a long time in here, if someone does
+ * full device discards (like mkfs). Be nice and allow
+ * us to schedule out to avoid softlocking if preempt
+ * is disabled.
+ */
+ cond_resched();
}
blk_finish_plug(&plug);
--
1.9.0
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