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BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff8881005b3138 of 8 bytes by task 17794 on cpu 0:
 write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
 do_writepages+0x20f/0x340 mm/page-writeback.c:2558
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 filemap_write_and_wait_range+0xe0/0x210 mm/filemap.c:678
 filemap_write_and_wait include/linux/pagemap.h:64 [inline]
 sync_blockdev+0x42/0x50 block/bdev.c:198
 bdev_disk_changed+0x10b/0xbd0 block/partitions/core.c:663
 blkdev_get_whole+0x227/0x240 block/bdev.c:653
 blkdev_get_by_dev+0x236/0x390 block/bdev.c:795
 blkdev_open+0xf7/0x1e0 block/fops.c:589
 do_dentry_open+0x5c3/0xae0 fs/open.c:929
 vfs_open+0x4a/0x50 fs/open.c:1063
 do_open fs/namei.c:3639 [inline]
 path_openat+0x17f2/0x1d10 fs/namei.c:3796
 do_filp_open+0xf6/0x200 fs/namei.c:3823
 do_sys_openat2+0xab/0x110 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881005b3138 of 8 bytes by task 25626 on cpu 1:
 write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
 do_writepages+0x20f/0x340 mm/page-writeback.c:2558
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 filemap_write_and_wait_range+0xe0/0x210 mm/filemap.c:678
 filemap_write_and_wait include/linux/pagemap.h:64 [inline]
 sync_blockdev block/bdev.c:198 [inline]
 bdev_mark_dead+0x8e/0x110 block/bdev.c:965
 disk_force_media_change+0xb6/0xe0 block/disk-events.c:303
 __loop_clr_fd+0x248/0x3b0 drivers/block/loop.c:1174
 loop_clr_fd drivers/block/loop.c:1257 [inline]
 lo_ioctl+0xe93/0x12e0 drivers/block/loop.c:1563
 blkdev_ioctl+0x375/0x460 block/ioctl.c:630
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0x000000000000004f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25626 Comm: syz-executor.1 Not tainted 6.6.0-rc1-syzkaller-00033-g3669558bdf35 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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