====================================================== WARNING: possible circular locking dependency detected 6.14.0-rc4-syzkaller-00015-g2a1944bff549 #0 Not tainted ------------------------------------------------------ kswapd0/80 is trying to acquire lock: ffff88803faeaf98 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_reclaim_inode fs/xfs/xfs_icache.c:1037 [inline] ffff88803faeaf98 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1729 [inline] ffff88803faeaf98 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_icwalk_ag+0x1211/0x1ac0 fs/xfs/xfs_icache.c:1811 but task is already holding lock: ffffffff8ec3a200 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline] ffffffff8ec3a200 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __fs_reclaim_acquire mm/page_alloc.c:3853 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3867 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4066 [inline] slab_alloc_node mm/slub.c:4144 [inline] kmem_cache_alloc_node_noprof+0x48/0x380 mm/slub.c:4216 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:596 alloc_skb include/linux/skbuff.h:1331 [inline] alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410 kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608 kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207 bus_uevent_store+0x116/0x170 drivers/base/bus.c:832 kernfs_fop_write_iter+0x3a0/0x500 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:586 [inline] vfs_write+0xacf/0xd10 fs/read_write.c:679 ksys_write+0x18f/0x2b0 fs/read_write.c:731 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (uevent_sock_mutex){+.+.}-{4:4}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730 uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] kobject_uevent_net_broadcast+0x280/0x580 lib/kobject_uevent.c:410 kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608 loop_set_size drivers/block/loop.c:235 [inline] loop_set_status+0x4f8/0x800 drivers/block/loop.c:1292 lo_ioctl+0xce6/0x2870 blkdev_ioctl+0x5d0/0x6f0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#17){++++}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 bio_queue_enter block/blk.h:77 [inline] blk_mq_submit_bio+0x14e1/0x25a0 block/blk-mq.c:3091 __submit_bio+0x2cf/0x6a0 block/blk-core.c:628 __submit_bio_noacct_mq block/blk-core.c:715 [inline] submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:744 xfs_buf_submit_bio fs/xfs/xfs_buf.c:1558 [inline] xfs_buf_submit+0xa71/0xf40 fs/xfs/xfs_buf.c:1666 _xfs_buf_read fs/xfs/xfs_buf.c:806 [inline] xfs_buf_read_map+0x40f/0xa50 fs/xfs/xfs_buf.c:873 xfs_trans_read_buf_map+0x260/0xab0 fs/xfs/xfs_trans_buf.c:304 xfs_trans_read_buf fs/xfs/xfs_trans.h:212 [inline] xfs_read_agf+0x2dc/0x630 fs/xfs/libxfs/xfs_alloc.c:3378 xfs_alloc_read_agf+0x196/0xbe0 fs/xfs/libxfs/xfs_alloc.c:3413 xfs_alloc_fix_freelist+0x608/0x1bc0 fs/xfs/libxfs/xfs_alloc.c:2877 xfs_alloc_vextent_prepare_ag+0xf9/0x6b0 fs/xfs/libxfs/xfs_alloc.c:3543 xfs_alloc_vextent_iterate_ags+0x141/0x950 fs/xfs/libxfs/xfs_alloc.c:3727 xfs_alloc_vextent_start_ag+0x3f6/0x950 fs/xfs/libxfs/xfs_alloc.c:3816 xfs_bmap_btalloc_best_length fs/xfs/libxfs/xfs_bmap.c:3764 [inline] xfs_bmap_btalloc fs/xfs/libxfs/xfs_bmap.c:3809 [inline] xfs_bmapi_allocate+0x1af5/0x3650 fs/xfs/libxfs/xfs_bmap.c:4222 xfs_bmapi_write+0xb91/0x1b50 fs/xfs/libxfs/xfs_bmap.c:4551 xfs_dquot_disk_alloc+0x5f4/0xe20 fs/xfs/xfs_dquot.c:381 xfs_qm_dqread+0x1a3/0x630 fs/xfs/xfs_dquot.c:720 xfs_qm_dqget+0x2bb/0x6f0 fs/xfs/xfs_dquot.c:932 xfs_qm_quotacheck_dqadjust+0xeb/0x5e0 fs/xfs/xfs_qm.c:1333 xfs_qm_dqusage_adjust+0x5e1/0x850 fs/xfs/xfs_qm.c:1459 xfs_iwalk_ag_recs+0x4e3/0x820 fs/xfs/xfs_iwalk.c:209 xfs_iwalk_run_callbacks+0x218/0x470 fs/xfs/xfs_iwalk.c:370 xfs_iwalk_ag+0xa9a/0xbb0 fs/xfs/xfs_iwalk.c:476 xfs_iwalk_ag_work+0xfb/0x1b0 fs/xfs/xfs_iwalk.c:625 xfs_pwork_work+0x7f/0x190 fs/xfs/xfs_pwork.c:47 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3317 worker_thread+0x870/0xd30 kernel/workqueue.c:3398 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 (&xfs_nondir_ilock_class){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693 xfs_reclaim_inode fs/xfs/xfs_icache.c:1037 [inline] xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1729 [inline] xfs_icwalk_ag+0x1211/0x1ac0 fs/xfs/xfs_icache.c:1811 xfs_icwalk fs/xfs/xfs_icache.c:1859 [inline] xfs_reclaim_inodes_nr+0x2b0/0x390 fs/xfs/xfs_icache.c:1103 super_cache_scan+0x40f/0x4b0 fs/super.c:227 do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437 shrink_slab+0x1093/0x14d0 mm/shrinker.c:664 shrink_one+0x43b/0x850 mm/vmscan.c:4868 shrink_many mm/vmscan.c:4929 [inline] lru_gen_shrink_node mm/vmscan.c:5007 [inline] shrink_node+0x379b/0x3e20 mm/vmscan.c:5978 kswapd_shrink_node mm/vmscan.c:6807 [inline] balance_pgdat mm/vmscan.c:6999 [inline] kswapd+0x20f3/0x3b10 mm/vmscan.c:7264 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Chain exists of: &xfs_nondir_ilock_class --> uevent_sock_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(uevent_sock_mutex); lock(fs_reclaim); lock(&xfs_nondir_ilock_class); *** DEADLOCK *** 2 locks held by kswapd0/80: #0: ffffffff8ec3a200 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline] #0: ffffffff8ec3a200 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264 #1: ffff888011dea0e0 (&type->s_umount_key#53){++++}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff888011dea0e0 (&type->s_umount_key#53){++++}-{4:4}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196 stack backtrace: CPU: 0 UID: 0 PID: 80 Comm: kswapd0 Not tainted 6.14.0-rc4-syzkaller-00015-g2a1944bff549 #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: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208 check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693 xfs_reclaim_inode fs/xfs/xfs_icache.c:1037 [inline] xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1729 [inline] xfs_icwalk_ag+0x1211/0x1ac0 fs/xfs/xfs_icache.c:1811 xfs_icwalk fs/xfs/xfs_icache.c:1859 [inline] xfs_reclaim_inodes_nr+0x2b0/0x390 fs/xfs/xfs_icache.c:1103 super_cache_scan+0x40f/0x4b0 fs/super.c:227 do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437 shrink_slab+0x1093/0x14d0 mm/shrinker.c:664 shrink_one+0x43b/0x850 mm/vmscan.c:4868 shrink_many mm/vmscan.c:4929 [inline] lru_gen_shrink_node mm/vmscan.c:5007 [inline] shrink_node+0x379b/0x3e20 mm/vmscan.c:5978 kswapd_shrink_node mm/vmscan.c:6807 [inline] balance_pgdat mm/vmscan.c:6999 [inline] kswapd+0x20f3/0x3b10 mm/vmscan.c:7264 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244