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BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

write to 0xffff8881050b6314 of 4 bytes by task 8681 on cpu 0:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark lib/xarray.c:893 [inline]
 __xa_set_mark+0x182/0x1b0 lib/xarray.c:1939
 __folio_mark_dirty+0x3b5/0x4e0 mm/page-writeback.c:2798
 mark_buffer_dirty+0x148/0x250 fs/buffer.c:1201
 __block_commit_write fs/buffer.c:2194 [inline]
 block_write_end+0x123/0x210 fs/buffer.c:2270
 generic_write_end+0x5c/0x160 fs/buffer.c:2284
 fat_write_end+0x4e/0x160 fs/fat/inode.c:242
 generic_perform_write+0x33c/0x4a0 mm/filemap.c:4069
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4155
 generic_file_write_iter+0x77/0x1c0 mm/filemap.c:4181
 iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x39b/0x970 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
 x64_sys_call+0xed5/0x2d60 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

read to 0xffff8881050b6314 of 4 bytes by task 8666 on cpu 1:
 xa_marked include/linux/xarray.h:424 [inline]
 xas_find_marked+0x60a/0x660 lib/xarray.c:1343
 find_get_entry+0x54/0x390 mm/filemap.c:1994
 filemap_get_folios_tag+0x9e/0x210 mm/filemap.c:2261
 __filemap_fdatawait_range mm/filemap.c:524 [inline]
 file_write_and_wait_range+0x162/0x250 mm/filemap.c:792
 __generic_file_fsync+0x46/0x140 fs/libfs.c:1528
 fat_file_fsync+0x46/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x116/0x130 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2871 [inline]
 generic_file_write_iter+0x185/0x1c0 mm/filemap.c:4185
 iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x39b/0x970 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
 x64_sys_call+0xed5/0x2d60 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: 0x04000021 -> 0x0e000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8666 Comm: syz.0.1753 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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