======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.1474/20878 is trying to acquire lock:
ffff888064c72800 (sb_internal#4){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6465

but task is already holding lock:
ffff888064c72688 (sb_pagefaults#5){.+.+}-{0:0}, at: do_page_mkwrite+0x14a/0x310 mm/memory.c:3816

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (sb_pagefaults#5){.+.+}-{0:0}:
       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/super.h:19 [inline]
       sb_start_pagefault include/linux/fs/super.h:159 [inline]
       btrfs_page_mkwrite+0x32b/0x1a50 fs/btrfs/file.c:1837
       do_page_mkwrite+0x14a/0x310 mm/memory.c:3816
       do_shared_fault mm/memory.c:6076 [inline]
       do_fault mm/memory.c:6138 [inline]
       do_pte_missing+0x734/0x28f0 mm/memory.c:4700
       handle_pte_fault mm/memory.c:6558 [inline]
       __handle_mm_fault mm/memory.c:6707 [inline]
       handle_mm_fault+0xf64/0x28c0 mm/memory.c:6876
       do_user_addr_fault+0x746/0x1340 arch/x86/mm/fault.c:1394
       handle_page_fault arch/x86/mm/fault.c:1483 [inline]
       exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

-> #5 (&mm->mmap_lock){++++}-{4:4}:
       down_read_killable+0xa4/0x220 kernel/locking/rwsem.c:1599
       mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:609
       get_mmap_lock_carefully mm/mmap_lock.c:450 [inline]
       lock_mm_and_find_vma+0x2d6/0x340 mm/mmap_lock.c:501
       do_user_addr_fault+0x343/0x1340 arch/x86/mm/fault.c:1366
       handle_page_fault arch/x86/mm/fault.c:1483 [inline]
       exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
       filldir+0x2bd/0x630 fs/readdir.c:-1
       dir_emit include/linux/fs.h:3607 [inline]
       kernfs_fop_readdir+0x583/0x960 fs/kernfs/dir.c:1999
       iterate_dir+0x2f1/0x4e0 fs/readdir.c:110
       __do_sys_getdents fs/readdir.c:319 [inline]
       __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&root->kernfs_rwsem){++++}-{4:4}:
       down_write+0x3a/0x50 kernel/locking/rwsem.c:1631
       kernfs_add_one+0x41/0x6f0 fs/kernfs/dir.c:825
       kernfs_create_dir_ns+0x1a1/0x230 fs/kernfs/dir.c:1130
       sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59
       create_dir lib/kobject.c:73 [inline]
       kobject_add_internal+0x62c/0xce0 lib/kobject.c:240
       kobject_add_varg lib/kobject.c:374 [inline]
       kobject_init_and_add+0x12b/0x1a0 lib/kobject.c:457
       btrfs_sysfs_add_qgroups+0x118/0x2f0 fs/btrfs/sysfs.c:2604
       btrfs_quota_enable+0x274/0x1e20 fs/btrfs/qgroup.c:1032
       btrfs_ioctl_quota_ctl+0x189/0x1f0 fs/btrfs/ioctl.c:3581
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580
       btrfs_quota_enable+0x2b1/0x1e20 fs/btrfs/qgroup.c:1061
       btrfs_ioctl_quota_ctl+0x189/0x1f0 fs/btrfs/ioctl.c:3581
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
       join_transaction+0x18a/0xc60 fs/btrfs/transaction.c:324
       start_transaction+0x6ed/0x17d0 fs/btrfs/transaction.c:729
       __cow_file_range_inline+0x161/0x1000 fs/btrfs/inode.c:625
       run_delalloc_inline fs/btrfs/inode.c:2373 [inline]
       btrfs_run_delalloc_range+0x15a8/0x1d90 fs/btrfs/inode.c:2434
       writepage_delalloc+0x10a4/0x1c60 fs/btrfs/extent_io.c:1710
       extent_writepage fs/btrfs/extent_io.c:2090 [inline]
       extent_write_cache_pages fs/btrfs/extent_io.c:2843 [inline]
       btrfs_writepages+0x1625/0x28c0 fs/btrfs/extent_io.c:2975
       do_writepages+0x338/0x560 mm/page-writeback.c:2560
       filemap_writeback mm/filemap.c:387 [inline]
       filemap_fdatawrite_range+0x1f2/0x300 mm/filemap.c:412
       btrfs_fdatawrite_range+0x54/0xf0 fs/btrfs/file.c:3860
       btrfs_direct_write+0x5d0/0xce0 fs/btrfs/direct-io.c:1046
       btrfs_do_write_iter+0x329/0x790 fs/btrfs/file.c:1427
       iter_file_splice_write+0xa36/0x1240 fs/splice.c:736
       do_splice_from fs/splice.c:936 [inline]
       direct_splice_actor+0x104/0x160 fs/splice.c:1159
       splice_direct_to_actor+0x586/0xcc0 fs/splice.c:1103
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x19b/0x2a0 fs/splice.c:1228
       do_sendfile+0x540/0x7e0 fs/read_write.c:1371
       __do_sys_sendfile64 fs/read_write.c:1432 [inline]
       __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1418
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
       join_transaction+0x169/0xc60 fs/btrfs/transaction.c:323
       start_transaction+0x6ed/0x17d0 fs/btrfs/transaction.c:729
       __cow_file_range_inline+0x161/0x1000 fs/btrfs/inode.c:625
       run_delalloc_inline fs/btrfs/inode.c:2373 [inline]
       btrfs_run_delalloc_range+0x15a8/0x1d90 fs/btrfs/inode.c:2434
       writepage_delalloc+0x10a4/0x1c60 fs/btrfs/extent_io.c:1710
       extent_writepage fs/btrfs/extent_io.c:2090 [inline]
       extent_write_cache_pages fs/btrfs/extent_io.c:2843 [inline]
       btrfs_writepages+0x1625/0x28c0 fs/btrfs/extent_io.c:2975
       do_writepages+0x338/0x560 mm/page-writeback.c:2560
       filemap_writeback mm/filemap.c:387 [inline]
       filemap_fdatawrite_range+0x1f2/0x300 mm/filemap.c:412
       btrfs_fdatawrite_range+0x54/0xf0 fs/btrfs/file.c:3860
       btrfs_direct_write+0x5d0/0xce0 fs/btrfs/direct-io.c:1046
       btrfs_do_write_iter+0x329/0x790 fs/btrfs/file.c:1427
       iter_file_splice_write+0xa36/0x1240 fs/splice.c:736
       do_splice_from fs/splice.c:936 [inline]
       direct_splice_actor+0x104/0x160 fs/splice.c:1159
       splice_direct_to_actor+0x586/0xcc0 fs/splice.c:1103
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x19b/0x2a0 fs/splice.c:1228
       do_sendfile+0x540/0x7e0 fs/read_write.c:1371
       __do_sys_sendfile64 fs/read_write.c:1432 [inline]
       __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1418
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal#4){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3209 [inline]
       check_prevs_add kernel/locking/lockdep.c:3328 [inline]
       validate_chain kernel/locking/lockdep.c:3952 [inline]
       __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
       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/super.h:19 [inline]
       sb_start_intwrite include/linux/fs/super.h:177 [inline]
       start_transaction+0x575/0x17d0 fs/btrfs/transaction.c:723
       btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6465
       file_update_time_flags+0x28b/0x450 fs/inode.c:2480
       btrfs_page_mkwrite+0x60b/0x1a50 fs/btrfs/file.c:1878
       do_page_mkwrite+0x14a/0x310 mm/memory.c:3816
       do_shared_fault mm/memory.c:6076 [inline]
       do_fault mm/memory.c:6138 [inline]
       do_pte_missing+0x734/0x28f0 mm/memory.c:4700
       handle_pte_fault mm/memory.c:6558 [inline]
       __handle_mm_fault mm/memory.c:6707 [inline]
       handle_mm_fault+0xf64/0x28c0 mm/memory.c:6876
       do_user_addr_fault+0x746/0x1340 arch/x86/mm/fault.c:1394
       handle_page_fault arch/x86/mm/fault.c:1483 [inline]
       exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

other info that might help us debug this:

Chain exists of:
  sb_internal#4 --> &mm->mmap_lock --> sb_pagefaults#5

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_pagefaults#5);
                               lock(&mm->mmap_lock);
                               lock(sb_pagefaults#5);
  rlock(sb_internal#4);

 *** DEADLOCK ***

locks held by syz.8.1474/20878: 2, last CPU#0:
 #0: ffff8880380f83b8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:619 [inline]
 #0: ffff8880380f83b8 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
 #0: ffff8880380f83b8 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340 mm/mmap_lock.c:501
 #1: ffff888064c72688 (sb_pagefaults#5){.+.+}-{0:0}, at: do_page_mkwrite+0x14a/0x310 mm/memory.c:3816

stack backtrace:
CPU: 0 UID: 0 PID: 20878 Comm: syz.8.1474 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219
 check_prev_add kernel/locking/lockdep.c:3209 [inline]
 check_prevs_add kernel/locking/lockdep.c:3328 [inline]
 validate_chain kernel/locking/lockdep.c:3952 [inline]
 __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
 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/super.h:19 [inline]
 sb_start_intwrite include/linux/fs/super.h:177 [inline]
 start_transaction+0x575/0x17d0 fs/btrfs/transaction.c:723
 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6465
 file_update_time_flags+0x28b/0x450 fs/inode.c:2480
 btrfs_page_mkwrite+0x60b/0x1a50 fs/btrfs/file.c:1878
 do_page_mkwrite+0x14a/0x310 mm/memory.c:3816
 do_shared_fault mm/memory.c:6076 [inline]
 do_fault mm/memory.c:6138 [inline]
 do_pte_missing+0x734/0x28f0 mm/memory.c:4700
 handle_pte_fault mm/memory.c:6558 [inline]
 __handle_mm_fault mm/memory.c:6707 [inline]
 handle_mm_fault+0xf64/0x28c0 mm/memory.c:6876
 do_user_addr_fault+0x746/0x1340 arch/x86/mm/fault.c:1394
 handle_page_fault arch/x86/mm/fault.c:1483 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7f49a21276c5
Code: 48 8b 04 24 48 85 c0 74 17 48 8b 74 24 10 48 0f ce 48 89 74 24 10 48 83 f8 01 0f 85 f0 02 00 00 48 8b 44 24 18 48 8b 54 24 10 <48> 89 10 e9 5a fe ff ff 48 8b 44 24 20 48 0b 44 24 28 75 30 48 8b
RSP: 002b:00007fff1d4c78a0 EFLAGS: 00010246
RAX: 0000200000001618 RBX: 0000000000000008 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00005555626493d8
RBP: 00007fff1d4c79c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000004
R13: 00007f49a24e5fac R14: 0000000000142678 R15: 00007fff1d4c79e0
 </TASK>