syzbot

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BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff8881004c11f8 of 8 bytes by task 30818 on cpu 1:
 write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
 blkdev_writepages+0x59/0x90 block/fops.c:426
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0x95/0xc0 mm/filemap.c:454
 sync_blockdev_nowait+0x36/0x50 block/bdev.c:189
 sync_filesystem+0xe0/0x180 fs/sync.c:60
 generic_shutdown_super+0x42/0x210 fs/super.c:625
 kill_block_super+0x2a/0x60 fs/super.c:1680
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7319
 deactivate_locked_super+0x7a/0x1c0 fs/super.c:477
 deactivate_super+0x9b/0xb0 fs/super.c:510
 cleanup_mnt+0x272/0x2e0 fs/namespace.c:1267
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1274
 task_work_run+0x135/0x1a0 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:108 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
 syscall_exit_to_user_mode+0xbc/0x130 kernel/entry/common.c:212
 do_syscall_64+0x65/0x120 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881004c11f8 of 8 bytes by task 30748 on cpu 0:
 write_cache_pages+0x123/0x740 mm/page-writeback.c:2411
 blkdev_writepages+0x59/0x90 block/fops.c:426
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1625
 writeback_sb_inodes+0x514/0xad0 fs/fs-writeback.c:1916
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1987
 wb_writeback+0x264/0x6e0 fs/fs-writeback.c:2094
 wb_check_background_flush fs/fs-writeback.c:2164 [inline]
 wb_do_writeback fs/fs-writeback.c:2252 [inline]
 wb_workfn+0x67f/0x8d0 fs/fs-writeback.c:2279
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2706
 worker_thread+0x525/0x730 kernel/workqueue.c:2787
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

value changed: 0x0000000000000000 -> 0x0000000000000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30748 Comm: kworker/u4:12 Not tainted 6.8.0-rc2-syzkaller-00031-g861c0981648f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: writeback wb_workfn (flush-7:1)
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netdevsim netdevsim3 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
tipc: Left network mode
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
team0: left allmulticast mode
team_slave_0: left allmulticast mode
team_slave_1: left allmulticast mode
team0: left promiscuous mode
team_slave_0: left promiscuous mode
team_slave_1: left promiscuous mode
bridge0: port 3(team0) entered disabled state
bridge_slave_1: left allmulticast mode
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
bond2 (unregistering): Released all slaves
bond1 (unregistering): Released all slaves
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): Released all slaves