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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>
hifive-unleashed-5.1
Ming Lei 2019-01-15 11:59:52 +08:00 committed by Linus Torvalds
parent 3719876809
commit fe76fc6aaf
1 changed files with 3 additions and 2 deletions
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5
lib/sbitmap.c
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@ -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;
}