====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.162/7186 is trying to acquire lock: ffff88802b5a2410 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:462 but task is already holding lock: ffff88802ff7b538 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (&type->i_mutex_dir_key#5){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_read+0x97/0x1f0 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:885 [inline] lookup_slow+0x46/0x70 fs/namei.c:1824 walk_component+0x2d2/0x400 fs/namei.c:2129 lookup_last fs/namei.c:2630 [inline] path_lookupat+0x163/0x430 fs/namei.c:2654 filename_lookup+0x212/0x570 fs/namei.c:2683 kern_path+0x35/0x50 fs/namei.c:2816 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:1867 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2091 [inline] btrfs_get_tree+0x433/0x1820 fs/btrfs/super.c:2125 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #6 (&fs_devs->device_list_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547 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:2462 btrfs_rebuild_free_space_tree+0x285/0x760 fs/btrfs/free-space-tree.c:1384 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3075 open_ctree+0x293a/0x3a10 fs/btrfs/disk-io.c:3617 btrfs_fill_super fs/btrfs/super.c:991 [inline] btrfs_get_tree_super fs/btrfs/super.c:1954 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2091 [inline] btrfs_get_tree+0xf55/0x1820 fs/btrfs/super.c:2125 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&fs_info->reloc_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547 btrfs_commit_transaction+0xedd/0x3950 fs/btrfs/transaction.c:2408 btrfs_rebuild_free_space_tree+0x285/0x760 fs/btrfs/free-space-tree.c:1384 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3075 open_ctree+0x293a/0x3a10 fs/btrfs/disk-io.c:3617 btrfs_fill_super fs/btrfs/super.c:991 [inline] btrfs_get_tree_super fs/btrfs/super.c:1954 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2091 [inline] btrfs_get_tree+0xf55/0x1820 fs/btrfs/super.c:2125 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (btrfs_trans_unblocked){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 wait_current_trans+0x22b/0x520 fs/btrfs/transaction.c:531 start_transaction+0x6a4/0x1620 fs/btrfs/transaction.c:702 btrfs_create_common+0x145/0x230 fs/btrfs/inode.c:6758 vfs_mknod+0x37f/0x3c0 fs/namei.c:4235 do_mknodat+0x385/0x4d0 fs/namei.c:-1 __do_sys_mknodat fs/namei.c:4313 [inline] __se_sys_mknodat fs/namei.c:4310 [inline] __x64_sys_mknodat+0xa7/0xc0 fs/namei.c:4310 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (sb_internal#2){.+.+}-{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:1799 [inline] sb_start_intwrite include/linux/fs.h:1982 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6244 inode_update_time fs/inode.c:2075 [inline] __file_update_time fs/inode.c:2304 [inline] file_update_time+0x34d/0x490 fs/inode.c:2334 btrfs_page_mkwrite+0x5dd/0x1a80 fs/btrfs/file.c:1916 do_page_mkwrite+0x14d/0x310 mm/memory.c:3361 wp_page_shared mm/memory.c:3762 [inline] do_wp_page+0x25b8/0x4910 mm/memory.c:3981 handle_pte_fault mm/memory.c:6068 [inline] __handle_mm_fault mm/memory.c:6195 [inline] handle_mm_fault+0x97c/0x3400 mm/memory.c:6364 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #2 (sb_pagefaults#3){.+.+}-{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:1799 [inline] sb_start_pagefault include/linux/fs.h:1964 [inline] btrfs_page_mkwrite+0x32c/0x1a80 fs/btrfs/file.c:1875 do_page_mkwrite+0x14d/0x310 mm/memory.c:3361 wp_page_shared mm/memory.c:3762 [inline] do_wp_page+0x25b8/0x4910 mm/memory.c:3981 handle_pte_fault mm/memory.c:6068 [inline] __handle_mm_fault mm/memory.c:6195 [inline] handle_mm_fault+0x97c/0x3400 mm/memory.c:6364 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #1 (vm_lock){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __vma_enter_locked+0x182/0x380 mm/mmap_lock.c:63 __vma_start_write+0x1e/0x120 mm/mmap_lock.c:87 vma_start_write include/linux/mmap_lock.h:297 [inline] mprotect_fixup+0x578/0x9c0 mm/mprotect.c:828 setup_arg_pages+0x53a/0xaa0 fs/exec.c:670 load_elf_binary+0xbad/0x2750 fs/binfmt_elf.c:1013 search_binary_handler fs/exec.c:1670 [inline] exec_binprm fs/exec.c:1702 [inline] bprm_execve+0x999/0x1450 fs/exec.c:1754 kernel_execve+0x8f0/0x9f0 fs/exec.c:1920 try_to_run_init_process+0x13/0x60 init/main.c:1397 kernel_init+0xad/0x1d0 init/main.c:1525 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (&mm->mmap_lock){++++}-{4:4}: 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 down_read_killable+0x9d/0x220 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:462 get_mmap_lock_carefully mm/mmap_lock.c:286 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:337 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir64+0x2c7/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3959 [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+0x3a5/0x580 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/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &mm->mmap_lock --> &fs_devs->device_list_mutex --> &type->i_mutex_dir_key#5 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&type->i_mutex_dir_key#5); lock(&fs_devs->device_list_mutex); lock(&type->i_mutex_dir_key#5); rlock(&mm->mmap_lock); *** DEADLOCK *** 2 locks held by syz.4.162/7186: #0: ffff888032437928 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1232 #1: ffff88802ff7b538 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101 stack backtrace: CPU: 1 UID: 0 PID: 7186 Comm: syz.4.162 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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 down_read_killable+0x9d/0x220 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:462 get_mmap_lock_carefully mm/mmap_lock.c:286 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:337 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:filldir64+0x2c7/0x690 fs/readdir.c:379 Code: e8 48 8b 44 24 50 49 89 44 24 08 48 8b 4c 24 08 48 8b 44 24 58 48 89 01 48 8b 04 24 8b 54 24 14 49 bc 00 00 00 00 00 fc ff df <66> 89 41 10 80 e2 0f 88 51 12 49 63 ee c6 44 29 13 00 4c 8d 79 13 RSP: 0018:ffffc9000447fc90 EFLAGS: 00050283 RAX: 0000000000000020 RBX: ffffc9000447fe38 RCX: 0000200000000ff0 RDX: 000000000000000a RSI: 0000200000000fd0 RDI: 0000200000001010 RBP: 00007ffffffff000 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed100602cb29 R12: dffffc0000000000 R13: ffff888025556c78 R14: 000000000000000a R15: 0000200000001010 dir_emit include/linux/fs.h:3959 [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+0x3a5/0x580 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/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f515310eec9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5148f55038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f5153366090 RCX: 00007f515310eec9 RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000005 RBP: 00007f5153191f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5153366128 R14: 00007f5153366090 R15: 00007ffd8fae2238 ---------------- Code disassembly (best guess): 0: e8 48 8b 44 24 call 0x24448b4d 5: 50 push %rax 6: 49 89 44 24 08 mov %rax,0x8(%r12) b: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx 10: 48 8b 44 24 58 mov 0x58(%rsp),%rax 15: 48 89 01 mov %rax,(%rcx) 18: 48 8b 04 24 mov (%rsp),%rax 1c: 8b 54 24 14 mov 0x14(%rsp),%edx 20: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 27: fc ff df * 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction 2e: 80 e2 0f and $0xf,%dl 31: 88 51 12 mov %dl,0x12(%rcx) 34: 49 63 ee movslq %r14d,%rbp 37: c6 44 29 13 00 movb $0x0,0x13(%rcx,%rbp,1) 3c: 4c 8d 79 13 lea 0x13(%rcx),%r15