6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bart Van Assche bvanassche@acm.org
commit 198f36f902ec7e99b645382505f74b87a4523ed9 upstream.
If preparing a write bio fails then blk_zone_wplug_bio_work() calls bio_endio() with zwplug->lock held. If a device mapper driver is stacked on top of the zoned block device then this results in nested locking of zwplug->lock. The resulting lockdep complaint is a false positive because this is nested locking and not recursive locking. Suppress this false positive by calling blk_zone_wplug_bio_io_error() without holding zwplug->lock. This is safe because no code in blk_zone_wplug_bio_io_error() depends on zwplug->lock being held. This patch suppresses the following lockdep complaint:
WARNING: possible recursive locking detected -------------------------------------------- kworker/3:0H/46 is trying to acquire lock: ffffff882968b830 (&zwplug->lock){-...}-{2:2}, at: blk_zone_write_plug_bio_endio+0x64/0x1f0
but task is already holding lock: ffffff88315bc230 (&zwplug->lock){-...}-{2:2}, at: blk_zone_wplug_bio_work+0x8c/0x48c
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&zwplug->lock); lock(&zwplug->lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by kworker/3:0H/46: #0: ffffff8809486758 ((wq_completion)sdd_zwplugs){+.+.}-{0:0}, at: process_one_work+0x1bc/0x65c #1: ffffffc085de3d70 ((work_completion)(&zwplug->bio_work)){+.+.}-{0:0}, at: process_one_work+0x1e4/0x65c #2: ffffff88315bc230 (&zwplug->lock){-...}-{2:2}, at: blk_zone_wplug_bio_work+0x8c/0x48c
stack backtrace: CPU: 3 UID: 0 PID: 46 Comm: kworker/3:0H Tainted: G W OE 6.12.38-android16-5-maybe-dirty-4k #1 8b362b6f76e3645a58cd27d86982bce10d150025 Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: Spacecraft board based on MALIBU (DT) Workqueue: sdd_zwplugs blk_zone_wplug_bio_work Call trace: dump_backtrace+0xfc/0x17c show_stack+0x18/0x28 dump_stack_lvl+0x40/0xa0 dump_stack+0x18/0x24 print_deadlock_bug+0x38c/0x398 __lock_acquire+0x13e8/0x2e1c lock_acquire+0x134/0x2b4 _raw_spin_lock_irqsave+0x5c/0x80 blk_zone_write_plug_bio_endio+0x64/0x1f0 bio_endio+0x9c/0x240 __dm_io_complete+0x214/0x260 clone_endio+0xe8/0x214 bio_endio+0x218/0x240 blk_zone_wplug_bio_work+0x204/0x48c process_one_work+0x26c/0x65c worker_thread+0x33c/0x498 kthread+0x110/0x134 ret_from_fork+0x10/0x20
Cc: stable@vger.kernel.org Cc: Damien Le Moal dlemoal@kernel.org Cc: Christoph Hellwig hch@lst.de Fixes: dd291d77cc90 ("block: Introduce zone write plugging") Signed-off-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Damien Le Moal dlemoal@kernel.org Link: https://lore.kernel.org/r/20250825182720.1697203-1-bvanassche@acm.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-zoned.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/block/blk-zoned.c +++ b/block/blk-zoned.c @@ -1281,14 +1281,14 @@ static void blk_zone_wplug_bio_work(stru struct block_device *bdev; unsigned long flags; struct bio *bio; + bool prepared;
/* * Submit the next plugged BIO. If we do not have any, clear * the plugged flag. */ - spin_lock_irqsave(&zwplug->lock, flags); - again: + spin_lock_irqsave(&zwplug->lock, flags); bio = bio_list_pop(&zwplug->bio_list); if (!bio) { zwplug->flags &= ~BLK_ZONE_WPLUG_PLUGGED; @@ -1296,13 +1296,14 @@ again: goto put_zwplug; }
- if (!blk_zone_wplug_prepare_bio(zwplug, bio)) { + prepared = blk_zone_wplug_prepare_bio(zwplug, bio); + spin_unlock_irqrestore(&zwplug->lock, flags); + + if (!prepared) { blk_zone_wplug_bio_io_error(zwplug, bio); goto again; }
- spin_unlock_irqrestore(&zwplug->lock, flags); - bdev = bio->bi_bdev;
/*