- Fix DM thin to work as a swap device by using 'limit_swap_bios' DM

target flag (initially added to allow swap to dm-crypt) to throttle
   the amount of outstanding swap bios.
 
 - Fix DM crypt soft lockup warnings by calling cond_resched() from the
   cpu intensive loop in dmcrypt_write().
 
 - Fix DM crypt to not access an uninitialized tasklet. This fix allows
   for consistent handling of IO completion, by _not_ needlessly punting
   to a workqueue when tasklets are not needed.
 
 - Fix DM core's alloc_dev() initialization for DM stats to check for
   and propagate alloc_percpu() failure.
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Merge tag 'for-6.3/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - Fix DM thin to work as a swap device by using 'limit_swap_bios' DM
   target flag (initially added to allow swap to dm-crypt) to throttle
   the amount of outstanding swap bios.

 - Fix DM crypt soft lockup warnings by calling cond_resched() from the
   cpu intensive loop in dmcrypt_write().

 - Fix DM crypt to not access an uninitialized tasklet. This fix allows
   for consistent handling of IO completion, by _not_ needlessly punting
   to a workqueue when tasklets are not needed.

 - Fix DM core's alloc_dev() initialization for DM stats to check for
   and propagate alloc_percpu() failure.

* tag 'for-6.3/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm stats: check for and propagate alloc_percpu failure
  dm crypt: avoid accessing uninitialized tasklet
  dm crypt: add cond_resched() to dmcrypt_write()
  dm thin: fix deadlock when swapping to thin device

drivers/md/dm-crypt.c

@@ -72,7 +72,9 @@ struct dm_crypt_io {
 	struct crypt_config *cc;
 	struct bio *base_bio;
 	u8 *integrity_metadata;
-	bool integrity_metadata_from_pool;
+	bool integrity_metadata_from_pool:1;
+	bool in_tasklet:1;
+
 	struct work_struct work;
 	struct tasklet_struct tasklet;
 
@@ -1730,6 +1732,7 @@ static void crypt_io_init(struct dm_crypt_io *io, struct crypt_config *cc,
 	io->ctx.r.req = NULL;
 	io->integrity_metadata = NULL;
 	io->integrity_metadata_from_pool = false;
+	io->in_tasklet = false;
 	atomic_set(&io->io_pending, 0);
 }
 
@@ -1776,14 +1779,13 @@ static void crypt_dec_pending(struct dm_crypt_io *io)
 	 * our tasklet. In this case we need to delay bio_endio()
 	 * execution to after the tasklet is done and dequeued.
 	 */
-	if (tasklet_trylock(&io->tasklet)) {
-		tasklet_unlock(&io->tasklet);
-		bio_endio(base_bio);
+	if (io->in_tasklet) {
+		INIT_WORK(&io->work, kcryptd_io_bio_endio);
+		queue_work(cc->io_queue, &io->work);
 		return;
 	}
 
-	INIT_WORK(&io->work, kcryptd_io_bio_endio);
-	queue_work(cc->io_queue, &io->work);
+	bio_endio(base_bio);
 }
 
 /*
@@ -1936,6 +1938,7 @@ pop_from_list:
 			io = crypt_io_from_node(rb_first(&write_tree));
 			rb_erase(&io->rb_node, &write_tree);
 			kcryptd_io_write(io);
+			cond_resched();
 		} while (!RB_EMPTY_ROOT(&write_tree));
 		blk_finish_plug(&plug);
 	}
@@ -2230,6 +2233,7 @@ static void kcryptd_queue_crypt(struct dm_crypt_io *io)
 		 * it is being executed with irqs disabled.
 		 */
 		if (in_hardirq() || irqs_disabled()) {
+			io->in_tasklet = true;
 			tasklet_init(&io->tasklet, kcryptd_crypt_tasklet, (unsigned long)&io->work);
 			tasklet_schedule(&io->tasklet);
 			return;

drivers/md/dm-stats.c

@@ -188,7 +188,7 @@ static int dm_stat_in_flight(struct dm_stat_shared *shared)
 	       atomic_read(&shared->in_flight[WRITE]);
 }
 
-void dm_stats_init(struct dm_stats *stats)
+int dm_stats_init(struct dm_stats *stats)
 {
 	int cpu;
 	struct dm_stats_last_position *last;
@@ -197,11 +197,16 @@ void dm_stats_init(struct dm_stats *stats)
 	INIT_LIST_HEAD(&stats->list);
 	stats->precise_timestamps = false;
 	stats->last = alloc_percpu(struct dm_stats_last_position);
+	if (!stats->last)
+		return -ENOMEM;
+
 	for_each_possible_cpu(cpu) {
 		last = per_cpu_ptr(stats->last, cpu);
 		last->last_sector = (sector_t)ULLONG_MAX;
 		last->last_rw = UINT_MAX;
 	}
+
+	return 0;
 }
 
 void dm_stats_cleanup(struct dm_stats *stats)

drivers/md/dm-stats.h

@@ -21,7 +21,7 @@ struct dm_stats_aux {
 	unsigned long long duration_ns;
 };
 
-void dm_stats_init(struct dm_stats *st);
+int dm_stats_init(struct dm_stats *st);
 void dm_stats_cleanup(struct dm_stats *st);
 
 struct mapped_device;

drivers/md/dm-thin.c

@@ -3369,6 +3369,7 @@ static int pool_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	pt->low_water_blocks = low_water_blocks;
 	pt->adjusted_pf = pt->requested_pf = pf;
 	ti->num_flush_bios = 1;
+	ti->limit_swap_bios = true;
 
 	/*
 	 * Only need to enable discards if the pool should pass
@@ -4249,6 +4250,7 @@ static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 
 	ti->num_flush_bios = 1;
+	ti->limit_swap_bios = true;
 	ti->flush_supported = true;
 	ti->accounts_remapped_io = true;
 	ti->per_io_data_size = sizeof(struct dm_thin_endio_hook);

drivers/md/dm.c

@@ -2097,7 +2097,9 @@ static struct mapped_device *alloc_dev(int minor)
 	if (!md->pending_io)
 		goto bad;
 
-	dm_stats_init(&md->stats);
+	r = dm_stats_init(&md->stats);
+	if (r < 0)
+		goto bad;
 
 	/* Populate the mapping, nobody knows we exist yet */
 	spin_lock(&_minor_lock);