======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.9.15175/10878 is trying to acquire lock:
ffff88816e3b2610 (sb_internal#5){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190

but task is already holding lock:
ffff88816e3b2518 (sb_pagefaults#11){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (sb_pagefaults#11){.+.+}-{0:0}:
       btrfs_page_mkwrite+0x319/0x1b00
       do_page_mkwrite+0x14d/0x310
       do_wp_page+0x267e/0x58b0
       handle_mm_fault+0x1520/0x32b0
       do_user_addr_fault+0xa73/0x1340
       exc_page_fault+0x6a/0xc0
       asm_exc_page_fault+0x26/0x30

-> #6 (vm_lock){++++}-{0:0}:
       __vma_start_exclude_readers+0x28a/0x940
       __vma_start_write+0x3f/0x1a0
       mprotect_fixup+0x690/0xb80
       setup_arg_pages+0x5af/0xc40
       load_elf_binary+0xc5e/0x2980
       bprm_execve+0x93d/0x1410
       kernel_execve+0x8ef/0x9e0
       try_to_run_init_process+0x13/0x60
       kernel_init+0xad/0x1d0
       ret_from_fork+0x51b/0xa40
       ret_from_fork_asm+0x1a/0x30

-> #5 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault+0xcb/0x130
       _copy_to_user+0x2c/0xb0
       fiemap_fill_next_extent+0x1dd/0x3c0
       iomap_fiemap+0x498/0x580
       ext4_fiemap+0x285/0x330
       do_vfs_ioctl+0x125a/0x1530
       __se_sys_ioctl+0x82/0x170
       do_syscall_64+0xe2/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&type->i_mutex_dir_key#3){++++}-{4:4}:
       down_read+0x47/0x2e0
       lookup_slow+0x46/0x70
       path_lookupat+0x3f5/0x8c0
       filename_lookup+0x256/0x5d0
       kern_path+0x35/0x50
       device_list_add+0xfcb/0x2250
       btrfs_scan_one_device+0x3ef/0x670
       btrfs_control_ioctl+0x128/0x360
       __se_sys_ioctl+0xfc/0x170
       do_syscall_64+0xe2/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&fs_devs->device_list_mutex){+.+.}-{4:4}:
       __mutex_lock+0x19f/0x1300
       btrfs_create_pending_block_groups+0x61d/0x1870
       __btrfs_end_transaction+0x140/0x640
       flush_space+0x35e/0xd30
       do_async_reclaim_metadata_space+0x11e/0x350
       btrfs_async_reclaim_metadata_space+0x89/0xe0
       process_scheduled_works+0xaec/0x17a0
       worker_thread+0x89f/0xd90
       kthread+0x726/0x8b0
       ret_from_fork+0x51b/0xa40
       ret_from_fork_asm+0x1a/0x30

-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
       join_transaction+0x1a4/0xd60
       start_transaction+0x6b9/0x15f0
       btrfs_dirty_inode+0x9f/0x190
       touch_atime+0x2f9/0x6d0
       filemap_read+0x1053/0x1230
       __kernel_read+0x504/0x9b0
       integrity_kernel_read+0x89/0xd0
       ima_calc_file_hash+0x12c3/0x17f0
       ima_collect_measurement+0x48b/0x930
       process_measurement+0x12e0/0x1cb0
       ima_file_check+0xdf/0x130
       security_file_post_open+0xb3/0x260
       path_openat+0x34cb/0x3e20
       do_filp_open+0x22d/0x490
       do_sys_openat2+0x12f/0x220
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xe2/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
       join_transaction+0x182/0xd60
       start_transaction+0x6b9/0x15f0
       btrfs_dirty_inode+0x9f/0x190
       touch_atime+0x2f9/0x6d0
       filemap_read+0x1053/0x1230
       __kernel_read+0x504/0x9b0
       integrity_kernel_read+0x89/0xd0
       ima_calc_file_hash+0x12c3/0x17f0
       ima_collect_measurement+0x48b/0x930
       process_measurement+0x12e0/0x1cb0
       ima_file_check+0xdf/0x130
       security_file_post_open+0xb3/0x260
       path_openat+0x34cb/0x3e20
       do_filp_open+0x22d/0x490
       do_sys_openat2+0x12f/0x220
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xe2/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal#5){.+.+}-{0:0}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0x106/0x330
       start_transaction+0x56e/0x15f0
       btrfs_dirty_inode+0x9f/0x190
       file_update_time_flags+0x387/0x4d0
       btrfs_page_mkwrite+0x5cf/0x1b00
       do_page_mkwrite+0x14d/0x310
       do_wp_page+0x267e/0x58b0
       handle_mm_fault+0x1520/0x32b0
       do_user_addr_fault+0xa73/0x1340
       exc_page_fault+0x6a/0xc0
       asm_exc_page_fault+0x26/0x30

other info that might help us debug this:

Chain exists of:
  sb_internal#5 --> vm_lock --> sb_pagefaults#11

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_pagefaults#11);
                               lock(vm_lock);
                               lock(sb_pagefaults#11);
  rlock(sb_internal#5);

 *** DEADLOCK ***

2 locks held by syz.9.15175/10878:
 #0: ffff888177c26808 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500
 #1: ffff88816e3b2518 (sb_pagefaults#11){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310

stack backtrace:
CPU: 0 UID: 0 PID: 10878 Comm: syz.9.15175 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2cf0
 lock_acquire+0x106/0x330
 start_transaction+0x56e/0x15f0
 btrfs_dirty_inode+0x9f/0x190
 file_update_time_flags+0x387/0x4d0
 btrfs_page_mkwrite+0x5cf/0x1b00
 do_page_mkwrite+0x14d/0x310
 do_wp_page+0x267e/0x58b0
 handle_mm_fault+0x1520/0x32b0
 do_user_addr_fault+0xa73/0x1340
 exc_page_fault+0x6a/0xc0
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x7fc1ee96bb98
Code: 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 0f 1f 00 48 8b 4c 16 f8 48 8b 36 <48> 89 37 48 89 4c 17 f8 c3 0f 10 54 16 f0 0f 10 5c 16 e0 0f 11 07
RSP: 002b:00007fffc4738ae8 EFLAGS: 00010246
RAX: 0000200000000040 RBX: 0000000000000004 RCX: 0031656c69662f2e
RDX: 0000000000000008 RSI: 0031656c69662f2e RDI: 0000200000000040
RBP: fffffffffffffffe R08: 0000001b2eb20000 R09: 0000000000000001
R10: 7ffffffffffffff7 R11: 0000000000000009 R12: 00007fffc4738c10
R13: 00007fc1eec15fac R14: 0000000000138934 R15: 00007fc1eec15fa0
 </TASK>
