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BUG: KCSAN: data-race in filemap_write_and_wait_range / xas_set_mark

write to 0xffff8881066b6014 of 4 bytes by task 8993 on cpu 0:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark+0x131/0x150 lib/xarray.c:899
 __folio_start_writeback+0x1e8/0x430 mm/page-writeback.c:3126
 __mpage_writepage+0xbed/0xe10 fs/mpage.c:619
 write_cache_pages+0x62/0x100 mm/page-writeback.c:2644
 mpage_writepages+0x72/0xf0 fs/mpage.c:666
 fat_writepages+0x24/0x30 fs/fat/inode.c:199
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2687
 filemap_fdatawrite_wbc mm/filemap.c:388 [inline]
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0x168/0x2f0 mm/filemap.c:796
 __generic_file_fsync+0x46/0x140 fs/libfs.c:1525
 fat_file_fsync+0x46/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x116/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:2970 [inline]
 generic_file_write_iter+0x1c3/0x310 mm/filemap.c:4233
 do_iter_readv_writev+0x403/0x4b0
 vfs_writev+0x2d9/0x880 fs/read_write.c:1050
 do_pwritev fs/read_write.c:1146 [inline]
 __do_sys_pwritev2 fs/read_write.c:1204 [inline]
 __se_sys_pwritev2+0x100/0x1c0 fs/read_write.c:1195
 __x64_sys_pwritev2+0x78/0x90 fs/read_write.c:1195
 x64_sys_call+0x2afe/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:329
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881066b6014 of 4 bytes by task 8998 on cpu 1:
 xa_marked include/linux/xarray.h:424 [inline]
 mapping_tagged include/linux/fs.h:539 [inline]
 filemap_fdatawrite_wbc mm/filemap.c:384 [inline]
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 filemap_write_and_wait_range+0xfc/0x360 mm/filemap.c:693
 __blockdev_direct_IO+0x461/0x1e80 fs/direct-io.c:1162
 blockdev_direct_IO include/linux/fs.h:3412 [inline]
 fat_direct_IO+0x10a/0x1d0 fs/fat/inode.c:281
 generic_file_read_iter+0x225/0x330 mm/filemap.c:2859
 copy_splice_read+0x383/0x5b0 fs/splice.c:365
 do_splice_read fs/splice.c:984 [inline]
 splice_direct_to_actor+0x28b/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0a000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8998 Comm: syz.3.1790 Not tainted 6.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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