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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_single_inode

write to 0xffff88810a12a528 of 4 bytes by task 4809 on cpu 0:
 writeback_single_inode+0x14a/0x3e0 fs/fs-writeback.c:1798
 sync_inode_metadata+0x5b/0x90 fs/fs-writeback.c:2883
 __generic_file_fsync+0xf8/0x140 fs/libfs.c:1537
 fat_file_fsync+0x49/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x10d/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:3031 [inline]
 generic_file_write_iter+0x1b8/0x2f0 mm/filemap.c:4259
 iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1158
 splice_direct_to_actor+0x312/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810a12a528 of 4 bytes by task 4814 on cpu 1:
 __mark_inode_dirty+0x52/0x760 fs/fs-writeback.c:2509
 fat_update_time+0x1ec/0x200 fs/fat/misc.c:357
 inode_update_time fs/inode.c:2076 [inline]
 touch_atime+0x145/0x340 fs/inode.c:2149
 file_accessed include/linux/fs.h:2652 [inline]
 filemap_splice_read+0x629/0x6b0 mm/filemap.c:3046
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000038 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4814 Comm: syz.3.429 Not tainted 6.16.0-rc2-syzkaller-00278-g3f75bfff44be #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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