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BUG: KCSAN: data-race in __xa_clear_mark / sync_inodes_sb

write to 0xffff88811f1904ac of 4 bytes by interrupt on cpu 1:
 xa_mark_clear lib/xarray.c:75 [inline]
 xas_clear_mark lib/xarray.c:918 [inline]
 __xa_clear_mark+0x325/0x350 lib/xarray.c:1726
 test_clear_page_writeback+0x28d/0x480 mm/page-writeback.c:2739
 end_page_writeback+0xa7/0x110 mm/filemap.c:1467
 ext4_finish_bio+0x429/0x490 fs/ext4/page-io.c:146
 ext4_end_bio+0x1bd/0x310 fs/ext4/page-io.c:367
 bio_endio+0x28a/0x370 block/bio.c:1449
 req_bio_endio block/blk-core.c:259 [inline]
 blk_update_request+0x535/0xbd0 block/blk-core.c:1577
 scsi_end_request+0x4e/0x400 drivers/scsi/scsi_lib.c:566
 scsi_io_completion+0x105/0xf40 drivers/scsi/scsi_lib.c:938
 scsi_finish_command+0x277/0x2c0 drivers/scsi/scsi.c:214
 scsi_softirq_done+0x271/0x400 drivers/scsi/scsi_lib.c:1464
 blk_done_softirq+0x1a5/0x200 block/blk-mq.c:586
 __do_softirq+0x198/0x360 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x5b/0x70 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:393 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:423
 common_interrupt+0x14e/0x1e0 arch/x86/kernel/irq.c:239
 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:572
 tomoyo_path_matches_pattern+0x2c/0x120 security/tomoyo/util.c:919
 tomoyo_compare_name_union security/tomoyo/file.c:87 [inline]
 tomoyo_check_path_acl+0x9b/0xe0 security/tomoyo/file.c:260
 tomoyo_check_acl+0xcc/0x220 security/tomoyo/domain.c:175
 tomoyo_path_permission security/tomoyo/file.c:586 [inline]
 tomoyo_path_perm+0x22f/0x330 security/tomoyo/file.c:838
 tomoyo_inode_getattr+0x18/0x20 security/tomoyo/tomoyo.c:123
 security_inode_getattr+0x7f/0xd0 security/security.c:1278
 vfs_getattr fs/stat.c:121 [inline]
 vfs_statx+0x118/0x2b0 fs/stat.c:206
 vfs_lstat include/linux/fs.h:3178 [inline]
 __do_sys_newlstat fs/stat.c:374 [inline]
 __se_sys_newlstat+0x46/0x250 fs/stat.c:368
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:368
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811f1904ac of 4 bytes by task 8721 on cpu 0:
 xa_marked include/linux/xarray.h:416 [inline]
 mapping_tagged include/linux/fs.h:493 [inline]
 wait_sb_inodes fs/fs-writeback.c:2418 [inline]
 sync_inodes_sb+0x30e/0x450 fs/fs-writeback.c:2561
 __sync_filesystem fs/sync.c:34 [inline]
 sync_filesystem+0xe4/0x160 fs/sync.c:67
 ovl_sync_fs+0x74/0x90 fs/overlayfs/super.c:281
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem+0x112/0x160 fs/sync.c:67
 generic_shutdown_super+0x42/0x210 fs/super.c:448
 kill_anon_super+0x23/0x40 fs/super.c:1108
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:165 [inline]
 exit_to_user_mode_prepare+0x1b2/0x210 kernel/entry/common.c:192
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:267
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8721 Comm: syz-executor.1 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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