======================================================
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:
<TASK>
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
</TASK>
----------------
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