syzbot

======================================================
WARNING: possible circular locking dependency detected
6.12.0-syzkaller-07834-g06afb0f36106 #0 Not tainted
------------------------------------------------------
kswapd0/112 is trying to acquire lock:
ffff88801f3f1438 (&q->q_usage_counter(io)#68){++++}-{0:0}, at: bio_queue_enter block/blk.h:79 [inline]
ffff88801f3f1438 (&q->q_usage_counter(io)#68){++++}-{0:0}, at: blk_mq_submit_bio+0x7ca/0x24c0 block/blk-mq.c:3092

but task is already holding lock:
ffffffff8df4de60 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xcd9/0x18f0 mm/vmscan.c:6976

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:3851 [inline]
       fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:3865
       might_alloc include/linux/sched/mm.h:318 [inline]
       slab_pre_alloc_hook mm/slub.c:4036 [inline]
       slab_alloc_node mm/slub.c:4114 [inline]
       __do_kmalloc_node mm/slub.c:4263 [inline]
       __kmalloc_node_noprof+0xb7/0x440 mm/slub.c:4270
       __kvmalloc_node_noprof+0xad/0x1a0 mm/util.c:658
       sbitmap_init_node+0x1ca/0x770 lib/sbitmap.c:132
       scsi_realloc_sdev_budget_map+0x2c7/0x610 drivers/scsi/scsi_scan.c:246
       scsi_add_lun+0x11b4/0x1fd0 drivers/scsi/scsi_scan.c:1106
       scsi_probe_and_add_lun+0x4fa/0xda0 drivers/scsi/scsi_scan.c:1287
       __scsi_add_device+0x24b/0x290 drivers/scsi/scsi_scan.c:1622
       ata_scsi_scan_host+0x215/0x780 drivers/ata/libata-scsi.c:4575
       async_run_entry_fn+0x9c/0x530 kernel/async.c:129
       process_one_work+0x958/0x1b30 kernel/workqueue.c:3229
       process_scheduled_works kernel/workqueue.c:3310 [inline]
       worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (&q->q_usage_counter(io)#68){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
       __bio_queue_enter+0x4c6/0x740 block/blk-core.c:361
       bio_queue_enter block/blk.h:79 [inline]
       blk_mq_submit_bio+0x7ca/0x24c0 block/blk-mq.c:3092
       __submit_bio+0x384/0x540 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x698/0xd70 block/blk-core.c:739
       submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868
       swap_writepage_bdev_async mm/page_io.c:449 [inline]
       __swap_writepage+0x3a3/0xf50 mm/page_io.c:472
       swap_writepage+0x403/0x1040 mm/page_io.c:288
       pageout+0x3b2/0xaa0 mm/vmscan.c:689
       shrink_folio_list+0x3025/0x42d0 mm/vmscan.c:1367
       evict_folios+0x6d6/0x1970 mm/vmscan.c:4589
       try_to_shrink_lruvec+0x612/0x9b0 mm/vmscan.c:4784
       shrink_one+0x3e3/0x7b0 mm/vmscan.c:4822
       shrink_many mm/vmscan.c:4885 [inline]
       lru_gen_shrink_node mm/vmscan.c:4963 [inline]
       shrink_node+0xbbc/0x3ed0 mm/vmscan.c:5943
       kswapd_shrink_node mm/vmscan.c:6771 [inline]
       balance_pgdat+0xc1f/0x18f0 mm/vmscan.c:6963
       kswapd+0x5f8/0xc30 mm/vmscan.c:7232
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&q->q_usage_counter(io)#68);
                               lock(fs_reclaim);
  rlock(&q->q_usage_counter(io)#68);

 *** DEADLOCK ***

1 lock held by kswapd0/112:
 #0: ffffffff8df4de60 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xcd9/0x18f0 mm/vmscan.c:6976

stack backtrace:
CPU: 3 UID: 0 PID: 112 Comm: kswapd0 Not tainted 6.12.0-syzkaller-07834-g06afb0f36106 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __bio_queue_enter+0x4c6/0x740 block/blk-core.c:361
 bio_queue_enter block/blk.h:79 [inline]
 blk_mq_submit_bio+0x7ca/0x24c0 block/blk-mq.c:3092
 __submit_bio+0x384/0x540 block/blk-core.c:629
 __submit_bio_noacct_mq block/blk-core.c:710 [inline]
 submit_bio_noacct_nocheck+0x698/0xd70 block/blk-core.c:739
 submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868
 swap_writepage_bdev_async mm/page_io.c:449 [inline]
 __swap_writepage+0x3a3/0xf50 mm/page_io.c:472
 swap_writepage+0x403/0x1040 mm/page_io.c:288
 pageout+0x3b2/0xaa0 mm/vmscan.c:689
 shrink_folio_list+0x3025/0x42d0 mm/vmscan.c:1367
 evict_folios+0x6d6/0x1970 mm/vmscan.c:4589
 try_to_shrink_lruvec+0x612/0x9b0 mm/vmscan.c:4784
 shrink_one+0x3e3/0x7b0 mm/vmscan.c:4822
 shrink_many mm/vmscan.c:4885 [inline]
 lru_gen_shrink_node mm/vmscan.c:4963 [inline]
 shrink_node+0xbbc/0x3ed0 mm/vmscan.c:5943
 kswapd_shrink_node mm/vmscan.c:6771 [inline]
 balance_pgdat+0xc1f/0x18f0 mm/vmscan.c:6963
 kswapd+0x5f8/0xc30 mm/vmscan.c:7232
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>