syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.163-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.251/4792 is trying to acquire lock:
ffff0000e5151838 (&ei->i_mmap_lock){++++}-{3:3}
, at: btrfs_page_mkwrite+0x530/0xde8 fs/btrfs/inode.c:8942

but task is already holding lock:
ffff0000d3a8c558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x144/0x37c mm/memory.c:2892

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (sb_pagefaults#2){.+.+}-{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+0x254/0xde8 fs/btrfs/inode.c:8914
       do_page_mkwrite+0x144/0x37c mm/memory.c:2892
       do_shared_fault mm/memory.c:4298 [inline]
       do_fault mm/memory.c:4366 [inline]
       handle_pte_fault mm/memory.c:4621 [inline]
       __handle_mm_fault mm/memory.c:4756 [inline]
       handle_mm_fault+0x1a20/0x3424 mm/memory.c:4854
       __do_page_fault arch/arm64/mm/fault.c:505 [inline]
       do_page_fault+0x700/0xb60 arch/arm64/mm/fault.c:605
       do_translation_fault+0xe8/0x138 arch/arm64/mm/fault.c:686
       do_mem_abort+0x70/0x1d8 arch/arm64/mm/fault.c:819
       el0_da+0x94/0x20c arch/arm64/kernel/entry-common.c:494
       el0t_64_sync_handler+0xc0/0xe4 arch/arm64/kernel/entry-common.c:629
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #5 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc8/0x128 mm/memory.c:5328
       filldir64+0x2bc/0x9e4 fs/readdir.c:335
       dir_emit_dot include/linux/fs.h:3678 [inline]
       dir_emit_dots include/linux/fs.h:3689 [inline]
       dcache_readdir+0x134/0x678 fs/libfs.c:196
       iterate_dir+0x1f4/0x4ec
       __do_sys_getdents64 fs/readdir.c:369 [inline]
       __se_sys_getdents64 fs/readdir.c:354 [inline]
       __arm64_sys_getdents64+0x1c4/0x4c4 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+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #4 (&type->i_mutex_dir_key#5){++++}-{3:3}:
       down_read+0xc0/0x398 kernel/locking/rwsem.c:1498
       inode_lock_shared include/linux/fs.h:799 [inline]
       lookup_slow+0x50/0x84 fs/namei.c:1679
       walk_component+0x394/0x4cc fs/namei.c:1976
       lookup_last fs/namei.c:2431 [inline]
       path_lookupat+0x13c/0x3d0 fs/namei.c:2455
       filename_lookup+0x1c4/0x4c8 fs/namei.c:2484
       kern_path+0x4c/0x194 fs/namei.c:2582
       lookup_bdev+0xc0/0x25c block/bdev.c:979
       device_matched fs/btrfs/volumes.c:568 [inline]
       btrfs_free_stale_devices+0x658/0x9ec fs/btrfs/volumes.c:608
       btrfs_forget_devices+0x5c/0x98 fs/btrfs/volumes.c:1395
       btrfs_control_ioctl+0x12c/0x248 fs/btrfs/super.c:2451
       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+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #3 (&fs_devs->device_list_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       write_all_supers+0x134c/0x3a6c fs/btrfs/disk-io.c:4159
       btrfs_sync_log+0x19c8/0x2294 fs/btrfs/tree-log.c:3327
       btrfs_sync_file+0x924/0xe60 fs/btrfs/file.c:2349
       vfs_fsync_range+0x168/0x188 fs/sync.c:188
       generic_write_sync include/linux/fs.h:2984 [inline]
       btrfs_file_write_iter+0x758/0xad8 fs/btrfs/file.c:2093
       call_write_iter include/linux/fs.h:2172 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x884/0xb44 fs/read_write.c:594
       ksys_write+0x15c/0x26c fs/read_write.c:647
       __do_sys_write fs/read_write.c:659 [inline]
       __se_sys_write fs/read_write.c:656 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
       __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+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #2 (&fs_info->tree_log_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       btrfs_sync_log+0x1904/0x2294 fs/btrfs/tree-log.c:3308
       btrfs_sync_file+0x924/0xe60 fs/btrfs/file.c:2349
       vfs_fsync_range+0x168/0x188 fs/sync.c:188
       generic_write_sync include/linux/fs.h:2984 [inline]
       btrfs_file_write_iter+0x758/0xad8 fs/btrfs/file.c:2093
       call_write_iter include/linux/fs.h:2172 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x884/0xb44 fs/read_write.c:594
       ksys_write+0x15c/0x26c fs/read_write.c:647
       __do_sys_write fs/read_write.c:659 [inline]
       __se_sys_write fs/read_write.c:656 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
       __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+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (sb_internal#3){.+.+}-{0:0}:
       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+0x644/0x1480 fs/btrfs/transaction.c:678
       btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:777
       btrfs_sync_file+0x808/0xe60 fs/btrfs/file.c:2316
       vfs_fsync_range+0x168/0x188 fs/sync.c:188
       generic_write_sync include/linux/fs.h:2984 [inline]
       btrfs_file_write_iter+0x758/0xad8 fs/btrfs/file.c:2093
       call_write_iter include/linux/fs.h:2172 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x884/0xb44 fs/read_write.c:594
       ksys_write+0x15c/0x26c fs/read_write.c:647
       __do_sys_write fs/read_write.c:659 [inline]
       __se_sys_write fs/read_write.c:656 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
       __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+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&ei->i_mmap_lock){++++}-{3:3}:
       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+0x32d4/0x7638 kernel/locking/lockdep.c:5012
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
       down_read+0xc0/0x398 kernel/locking/rwsem.c:1498
       btrfs_page_mkwrite+0x530/0xde8 fs/btrfs/inode.c:8942
       do_page_mkwrite+0x144/0x37c mm/memory.c:2892
       do_shared_fault mm/memory.c:4298 [inline]
       do_fault mm/memory.c:4366 [inline]
       handle_pte_fault mm/memory.c:4621 [inline]
       __handle_mm_fault mm/memory.c:4756 [inline]
       handle_mm_fault+0x1a20/0x3424 mm/memory.c:4854
       __do_page_fault arch/arm64/mm/fault.c:505 [inline]
       do_page_fault+0x700/0xb60 arch/arm64/mm/fault.c:605
       do_translation_fault+0xe8/0x138 arch/arm64/mm/fault.c:686
       do_mem_abort+0x70/0x1d8 arch/arm64/mm/fault.c:819
       el0_da+0x94/0x20c arch/arm64/kernel/entry-common.c:494
       el0t_64_sync_handler+0xc0/0xe4 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:
  &ei->i_mmap_lock --> &mm->mmap_lock --> sb_pagefaults#2

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_pagefaults#2);
                               lock(&mm->mmap_lock);
                               lock(sb_pagefaults#2);
  lock(&ei->i_mmap_lock);

 *** DEADLOCK ***

2 locks held by syz.2.251/4792:
 #0: ffff0000c7e68118 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 #0: ffff0000c7e68118 (&mm->mmap_lock){++++}-{3:3}, at: do_page_fault+0x66c/0xb60 arch/arm64/mm/fault.c:590
 #1: ffff0000d3a8c558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x144/0x37c mm/memory.c:2892

stack backtrace:
CPU: 0 PID: 4792 Comm: syz.2.251 Not tainted 5.15.163-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 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+0x32d4/0x7638 kernel/locking/lockdep.c:5012
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
 down_read+0xc0/0x398 kernel/locking/rwsem.c:1498
 btrfs_page_mkwrite+0x530/0xde8 fs/btrfs/inode.c:8942
 do_page_mkwrite+0x144/0x37c mm/memory.c:2892
 do_shared_fault mm/memory.c:4298 [inline]
 do_fault mm/memory.c:4366 [inline]
 handle_pte_fault mm/memory.c:4621 [inline]
 __handle_mm_fault mm/memory.c:4756 [inline]
 handle_mm_fault+0x1a20/0x3424 mm/memory.c:4854
 __do_page_fault arch/arm64/mm/fault.c:505 [inline]
 do_page_fault+0x700/0xb60 arch/arm64/mm/fault.c:605
 do_translation_fault+0xe8/0x138 arch/arm64/mm/fault.c:686
 do_mem_abort+0x70/0x1d8 arch/arm64/mm/fault.c:819
 el0_da+0x94/0x20c arch/arm64/kernel/entry-common.c:494
 el0t_64_sync_handler+0xc0/0xe4 arch/arm64/kernel/entry-common.c:629
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584