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commit fe76fc6aaf538df27708ffa3e5d549a6c8e16142
parent 3719876809e745b9db5293d418600c194bbf5c23
Author: Ming Lei <ming.lei@redhat.com>
Date:   Tue, 15 Jan 2019 11:59:52 +0800

sbitmap: Protect swap_lock from hardirq

Because we may call blk_mq_get_driver_tag() directly from
blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may
come and the above DEADLOCK is triggered.

Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to
fix this issue by using 'spin_lock_bh', which isn't enough because we
complete request from hardirq context direclty in case of multiqueue.

Cc: Clark Williams <williams@redhat.com>
Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Diffstat:
Mlib/sbitmap.c | 5+++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c @@ -27,8 +27,9 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) { unsigned long mask, val; bool ret = false; + unsigned long flags; - spin_lock_bh(&sb->map[index].swap_lock); + spin_lock_irqsave(&sb->map[index].swap_lock, flags); if (!sb->map[index].cleared) goto out_unlock; @@ -49,7 +50,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) ret = true; out_unlock: - spin_unlock_bh(&sb->map[index].swap_lock); + spin_unlock_irqrestore(&sb->map[index].swap_lock, flags); return ret; }