dm thin: irqsave must always be used with the pool->lock spinlock (5e3283e2) · Commits · 戴 / test

Commit ("dm thin: use per thin device deferred bio lists") incorrectly stopped disabling irqs when taking the pool's spinlock. Irqs must be disabled when taking the pool's spinlock otherwise a thread could spin_lock(), then get interrupted to service thin_endio() in interrupt context, which would then deadlock in spin_lock_irqsave(). Signed-off-by:

Joe Thornber <ejt@redhat.com> Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-thin.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -3101,6 +3101,7 @@ static int thin_ctr(struct dm_target ti, unsigned argc, char *argv)
		struct thin_c *tc;
		struct dm_dev pool_dev, origin_dev;
		struct mapped_device *pool_md;
		unsigned long flags;

		mutex_lock(&dm_thin_pool_table.mutex);

		@@ -3191,9 +3192,9 @@ static int thin_ctr(struct dm_target ti, unsigned argc, char *argv)

		mutex_unlock(&dm_thin_pool_table.mutex);

		spin_lock(&tc->pool->lock);
		spin_lock_irqsave(&tc->pool->lock, flags);
		list_add_tail_rcu(&tc->list, &tc->pool->active_thins);
		spin_unlock(&tc->pool->lock);
		spin_unlock_irqrestore(&tc->pool->lock, flags);
		/*
		* This synchronize_rcu() call is needed here otherwise we risk a
		* wake_worker() call finding no bios to process (because the newly

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