====================================================== WARNING: possible circular locking dependency detected 5.15.185-syzkaller #0 Not tainted ------------------------------------------------------ syz.1.372/5662 is trying to acquire lock: ffff0000ddc34650 (sb_internal#2){.+.+}-{0:0}, at: btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793 but task is already holding lock: ffff0000ddc34558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x13c/0x358 mm/memory.c:2922 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (sb_pagefaults#3){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1811 [inline] sb_start_pagefault include/linux/fs.h:1910 [inline] btrfs_page_mkwrite+0x210/0xcf0 fs/btrfs/inode.c:8922 do_page_mkwrite+0x13c/0x358 mm/memory.c:2922 wp_page_shared+0x14c/0x398 mm/memory.c:3259 do_wp_page+0x7c0/0x994 mm/memory.c:3360 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1770/0x2950 mm/memory.c:4883 __do_page_fault arch/arm64/mm/fault.c:505 [inline] do_page_fault+0x694/0xad4 arch/arm64/mm/fault.c:605 do_mem_abort+0x6c/0x1ac arch/arm64/mm/fault.c:819 el0_da+0x90/0x1fc arch/arm64/kernel/entry-common.c:494 el0t_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:629 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #3 (&mm->mmap_lock){++++}-{3:3}: __might_fault+0xc8/0x128 mm/memory.c:5357 filldir64+0x2bc/0x9e4 fs/readdir.c:335 dir_emit_dot include/linux/fs.h:3717 [inline] dir_emit_dots include/linux/fs.h:3728 [inline] dcache_readdir+0x140/0x65c fs/libfs.c:196 iterate_dir+0x1f0/0x4cc fs/readdir.c:-1 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64 fs/readdir.c:354 [inline] __arm64_sys_getdents64+0x11c/0x340 fs/readdir.c:354 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #2 (&type->i_mutex_dir_key#5){++++}-{3:3}: down_read+0xc0/0x390 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x4c/0x80 fs/namei.c:1679 walk_component+0x2b0/0x3a8 fs/namei.c:1976 lookup_last fs/namei.c:2431 [inline] path_lookupat+0x13c/0x3d0 fs/namei.c:2455 filename_lookup+0x180/0x414 fs/namei.c:2484 kern_path+0x4c/0x190 fs/namei.c:2582 lookup_bdev+0xbc/0x244 block/bdev.c:982 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x614/0x908 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x5c/0x98 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x130/0x248 fs/btrfs/super.c:2450 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #1 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 insert_dev_extents fs/btrfs/block-group.c:2399 [inline] btrfs_create_pending_block_groups+0x3b4/0xca8 fs/btrfs/block-group.c:2449 __btrfs_end_transaction+0x13c/0x608 fs/btrfs/transaction.c:1016 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1052 flush_space+0x400/0xbd8 fs/btrfs/space-info.c:674 btrfs_async_reclaim_data_space+0xe8/0x3f8 fs/btrfs/space-info.c:1169 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870 -> #0 (sb_internal#2){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1811 [inline] sb_start_intwrite include/linux/fs.h:1928 [inline] start_transaction+0x624/0x13f0 fs/btrfs/transaction.c:680 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793 btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436 btrfs_update_time+0x224/0x248 fs/btrfs/inode.c:6478 inode_update_time fs/inode.c:1893 [inline] file_update_time+0x2fc/0x390 fs/inode.c:2083 btrfs_page_mkwrite+0x408/0xcf0 fs/btrfs/inode.c:8938 do_page_mkwrite+0x13c/0x358 mm/memory.c:2922 wp_page_shared+0x14c/0x398 mm/memory.c:3259 do_wp_page+0x7c0/0x994 mm/memory.c:3360 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1770/0x2950 mm/memory.c:4883 __do_page_fault arch/arm64/mm/fault.c:505 [inline] do_page_fault+0x694/0xad4 arch/arm64/mm/fault.c:605 do_mem_abort+0x6c/0x1ac arch/arm64/mm/fault.c:819 el0_da+0x90/0x1fc arch/arm64/kernel/entry-common.c:494 el0t_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:629 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: sb_internal#2 --> &mm->mmap_lock --> sb_pagefaults#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_pagefaults#3); lock(&mm->mmap_lock); lock(sb_pagefaults#3); lock(sb_internal#2); *** DEADLOCK *** 2 locks held by syz.1.372/5662: #0: ffff0000d3989258 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff0000d3989258 (&mm->mmap_lock){++++}-{3:3}, at: do_page_fault+0x364/0xad4 arch/arm64/mm/fault.c:586 #1: ffff0000ddc34558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x13c/0x358 mm/memory.c:2922 stack backtrace: CPU: 1 PID: 5662 Comm: syz.1.372 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1811 [inline] sb_start_intwrite include/linux/fs.h:1928 [inline] start_transaction+0x624/0x13f0 fs/btrfs/transaction.c:680 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793 btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436 btrfs_update_time+0x224/0x248 fs/btrfs/inode.c:6478 inode_update_time fs/inode.c:1893 [inline] file_update_time+0x2fc/0x390 fs/inode.c:2083 btrfs_page_mkwrite+0x408/0xcf0 fs/btrfs/inode.c:8938 do_page_mkwrite+0x13c/0x358 mm/memory.c:2922 wp_page_shared+0x14c/0x398 mm/memory.c:3259 do_wp_page+0x7c0/0x994 mm/memory.c:3360 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1770/0x2950 mm/memory.c:4883 __do_page_fault arch/arm64/mm/fault.c:505 [inline] do_page_fault+0x694/0xad4 arch/arm64/mm/fault.c:605 do_mem_abort+0x6c/0x1ac arch/arm64/mm/fault.c:819 el0_da+0x90/0x1fc arch/arm64/kernel/entry-common.c:494 el0t_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:629 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584