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BUG: KCSAN: data-race in __mark_inode_dirty / __mark_inode_dirty

write to 0xffff888135483120 of 8 bytes by task 23578 on cpu 0:
 __mark_inode_dirty+0x1c4/0x680 fs/fs-writeback.c:2433
 mark_inode_dirty include/linux/fs.h:2403 [inline]
 generic_write_end+0x157/0x180 fs/buffer.c:2198
 fat_write_end+0x4a/0x160 fs/fat/inode.c:249
 generic_perform_write+0x22a/0x3c0 mm/filemap.c:3667
 __generic_file_write_iter+0x161/0x300 mm/filemap.c:3783
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3815
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888135483120 of 8 bytes by task 23602 on cpu 1:
 __mark_inode_dirty+0xda/0x680 fs/fs-writeback.c:2419
 fat_update_time+0x125/0x140 fs/fat/misc.c:348
 update_time fs/inode.c:1784 [inline]
 touch_atime+0x11c/0x240 fs/inode.c:1856
 file_accessed include/linux/fs.h:2455 [inline]
 generic_file_splice_read+0x284/0x310 fs/splice.c:314
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000804 -> 0x0000000000000007

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23602 Comm: syz-executor.5 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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