====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.9.1831/11757 is trying to acquire lock: ffff88805f8e4610 (sb_internal#4){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6270 but task is already holding lock: ffff88805f8e4518 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3488 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (sb_pagefaults#6){.+.+}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1916 [inline] sb_start_pagefault include/linux/fs.h:2081 [inline] btrfs_page_mkwrite+0x317/0x1a70 fs/btrfs/file.c:1874 do_page_mkwrite+0x14d/0x310 mm/memory.c:3488 do_shared_fault mm/memory.c:5774 [inline] do_fault mm/memory.c:5836 [inline] do_pte_missing mm/memory.c:4361 [inline] handle_pte_fault mm/memory.c:6177 [inline] __handle_mm_fault+0x1916/0x5400 mm/memory.c:6318 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6487 do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 -> #6 (&mm->mmap_lock){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write_killable+0xa7/0x230 kernel/locking/rwsem.c:1601 mmap_write_lock_killable include/linux/mmap_lock.h:330 [inline] upgrade_mmap_lock_carefully+0xba/0x1c0 mm/mmap_lock.c:401 lock_mm_and_find_vma+0x10a/0x300 mm/mmap_lock.c:454 do_user_addr_fault+0x331/0x1380 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 filldir64+0x2c1/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3986 [inline] offset_dir_emit fs/libfs.c:507 [inline] offset_iterate_dir fs/libfs.c:523 [inline] offset_readdir+0x44c/0x560 fs/libfs.c:572 iterate_dir+0x399/0x570 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&type->i_mutex_dir_key#5){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:995 [inline] lookup_slow+0x46/0x70 fs/namei.c:1832 walk_component+0x2d2/0x400 fs/namei.c:2151 lookup_last fs/namei.c:2652 [inline] path_lookupat+0x163/0x430 fs/namei.c:2676 filename_lookup+0x212/0x570 fs/namei.c:2705 kern_path+0x35/0x50 fs/namei.c:2863 is_same_device fs/btrfs/volumes.c:759 [inline] device_list_add+0xe2a/0x22a0 fs/btrfs/volumes.c:894 btrfs_scan_one_device+0x3ee/0x650 fs/btrfs/volumes.c:1493 btrfs_get_tree_super fs/btrfs/super.c:1865 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline] btrfs_get_tree+0x438/0x1830 fs/btrfs/super.c:2123 vfs_get_tree+0x92/0x2b0 fs/super.c:1751 fc_mount fs/namespace.c:1208 [inline] do_new_mount_fc fs/namespace.c:3651 [inline] do_new_mount+0x302/0xa10 fs/namespace.c:3727 do_mount fs/namespace.c:4050 [inline] __do_sys_mount fs/namespace.c:4238 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4215 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&fs_devs->device_list_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 btrfs_run_dev_stats+0x102/0x10e0 fs/btrfs/volumes.c:7777 commit_cowonly_roots+0x1b2/0x860 fs/btrfs/transaction.c:1348 btrfs_commit_transaction+0xfc7/0x3950 fs/btrfs/transaction.c:2459 sync_filesystem+0x1cf/0x230 fs/sync.c:66 generic_shutdown_super+0x6f/0x2c0 fs/super.c:621 kill_anon_super+0x3b/0x70 fs/super.c:1281 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2129 deactivate_locked_super+0xbc/0x130 fs/super.c:473 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327 task_work_run+0x1d4/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->reloc_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 btrfs_record_root_in_trans+0x14f/0x180 fs/btrfs/transaction.c:503 start_transaction+0x3a4/0x1620 fs/btrfs/transaction.c:779 btrfs_fileattr_set+0x613/0xd20 fs/btrfs/ioctl.c:372 vfs_fileattr_set+0x932/0xb90 fs/file_attr.c:298 ioctl_setflags+0x17b/0x200 fs/file_attr.c:336 do_vfs_ioctl+0x8ed/0x1430 fs/ioctl.c:560 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_fileattr_set+0x613/0xd20 fs/btrfs/ioctl.c:372 vfs_fileattr_set+0x932/0xb90 fs/file_attr.c:298 ioctl_setflags+0x17b/0x200 fs/file_attr.c:336 do_vfs_ioctl+0x8ed/0x1430 fs/ioctl.c:560 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 join_transaction+0x182/0xd70 fs/btrfs/transaction.c:320 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_fileattr_set+0x613/0xd20 fs/btrfs/ioctl.c:372 vfs_fileattr_set+0x932/0xb90 fs/file_attr.c:298 ioctl_setflags+0x17b/0x200 fs/file_attr.c:336 do_vfs_ioctl+0x8ed/0x1430 fs/ioctl.c:560 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#4){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1916 [inline] sb_start_intwrite include/linux/fs.h:2099 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6270 inode_update_time fs/inode.c:2117 [inline] __file_update_time fs/inode.c:2345 [inline] file_update_time+0x347/0x490 fs/inode.c:2375 btrfs_page_mkwrite+0x5c8/0x1a70 fs/btrfs/file.c:1915 do_page_mkwrite+0x14d/0x310 mm/memory.c:3488 do_shared_fault mm/memory.c:5774 [inline] do_fault mm/memory.c:5836 [inline] do_pte_missing mm/memory.c:4361 [inline] handle_pte_fault mm/memory.c:6177 [inline] __handle_mm_fault+0x1916/0x5400 mm/memory.c:6318 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6487 do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 other info that might help us debug this: Chain exists of: sb_internal#4 --> &mm->mmap_lock --> sb_pagefaults#6 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_pagefaults#6); lock(&mm->mmap_lock); lock(sb_pagefaults#6); rlock(sb_internal#4); *** DEADLOCK *** 2 locks held by syz.9.1831/11757: #0: ffff88813ff1cd20 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:387 [inline] #0: ffff88813ff1cd20 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:368 [inline] #0: ffff88813ff1cd20 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/mmap_lock.c:428 #1: ffff88805f8e4518 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3488 stack backtrace: CPU: 0 UID: 0 PID: 11757 Comm: syz.9.1831 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1916 [inline] sb_start_intwrite include/linux/fs.h:2099 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6270 inode_update_time fs/inode.c:2117 [inline] __file_update_time fs/inode.c:2345 [inline] file_update_time+0x347/0x490 fs/inode.c:2375 btrfs_page_mkwrite+0x5c8/0x1a70 fs/btrfs/file.c:1915 do_page_mkwrite+0x14d/0x310 mm/memory.c:3488 do_shared_fault mm/memory.c:5774 [inline] do_fault mm/memory.c:5836 [inline] do_pte_missing mm/memory.c:4361 [inline] handle_pte_fault mm/memory.c:6177 [inline] __handle_mm_fault+0x1916/0x5400 mm/memory.c:6318 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6487 do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7f8c9815635b Code: fa 10 73 2d 83 fa 08 73 46 83 fa 04 73 16 83 fa 01 7c 10 8a 0e 74 0a 0f b7 74 16 fe 66 89 74 17 fe 88 0f c3 8b 4c 16 fc 8b 36 <89> 4c 17 fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 RSP: 002b:00007ffcf5f83c88 EFLAGS: 00010202 RAX: 0000200000000080 RBX: 0000000000000004 RCX: 0000000000737562 RDX: 0000000000000006 RSI: 0000000075622f2e RDI: 0000200000000080 RBP: 00007f8c983e7da0 R08: 0000001b30d20000 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000009 R12: 00007f8c983e5fac R13: 00007f8c983e5fa0 R14: fffffffffffffffe R15: 00007ffcf5f83da0