dm crypt: add cond_resched() to dmcrypt_write()

Mikulas Patocka · Mike Snitzer · commit fb294b1c0ba9 · 2023-03-06T16:50:12.000-05:00
The loop in dmcrypt_write may be running for unbounded amount of time, thus we need cond_resched() in it. This commit fixes the following warning: [ 3391.153255][ C12] watchdog: BUG: soft lockup - CPU#12 stuck for 23s! [dmcrypt_write/2:2897] ... [ 3391.387210][ C12] Call trace: [ 3391.390338][ C12] blk_attempt_bio_merge.part.6+0x38/0x158 [ 3391.395970][ C12] blk_attempt_plug_merge+0xc0/0x1b0 [ 3391.401085][ C12] blk_mq_submit_bio+0x398/0x550 [ 3391.405856][ C12] submit_bio_noacct+0x308/0x380 [ 3391.410630][ C12] dmcrypt_write+0x1e4/0x208 [dm_crypt] [ 3391.416005][ C12] kthread+0x130/0x138 [ 3391.419911][ C12] ret_from_fork+0x10/0x18 Reported-by: yangerkun <yangerkun@huawei.com> Fixes: dc26762 ("dm crypt: offload writes to thread") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
@@ -1937,6 +1937,7 @@ static int dmcrypt_write(void *data)
 			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);
 	}

Original file line number	Diff line number	Diff line change
`@@ -1937,6 +1937,7 @@ static int dmcrypt_write(void *data)`
`1937`	`1937`	`io = crypt_io_from_node(rb_first(&write_tree));`
`1938`	`1938`	`rb_erase(&io->rb_node, &write_tree);`
`1939`	`1939`	`kcryptd_io_write(io);`
	`1940`	`+ cond_resched();`
`1940`	`1941`	`} while (!RB_EMPTY_ROOT(&write_tree));`
`1941`	`1942`	`blk_finish_plug(&plug);`
`1942`	`1943`	`}`