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BUG: KCSAN: data-race in __mark_inode_dirty / __mark_inode_dirty

write to 0xffff888117c741a0 of 8 bytes by task 20328 on cpu 0:
 __mark_inode_dirty+0x1c1/0x940 fs/fs-writeback.c:2289
 mark_buffer_dirty+0x28b/0x2b0 fs/buffer.c:1156
 __block_commit_write.isra.0+0x11d/0x170 fs/buffer.c:2081
 block_write_end+0x6d/0x140 fs/buffer.c:2159
 generic_write_end+0x8c/0x1f0 fs/buffer.c:2173
 fat_write_end+0x57/0x120 fs/fat/inode.c:250
 generic_perform_write+0x1d7/0x320 mm/filemap.c:3298
 __generic_file_write_iter+0x2d7/0x370 mm/filemap.c:3384
 generic_file_write_iter+0x294/0x38e mm/filemap.c:3448
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:693
 do_iter_write fs/read_write.c:998 [inline]
 do_iter_write+0x137/0x3a0 fs/read_write.c:979
 vfs_iter_write+0x56/0x80 fs/read_write.c:1039
 iter_file_splice_write+0x530/0x830 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888117c741a0 of 8 bytes by task 20347 on cpu 1:
 __mark_inode_dirty+0xb6/0x940 fs/fs-writeback.c:2272
 fat_update_time fs/fat/misc.c:347 [inline]
 fat_update_time+0x1a1/0x1b0 fs/fat/misc.c:330
 update_time+0x53/0x90 fs/inode.c:1693
 touch_atime+0x13f/0x150 fs/inode.c:1765
 file_accessed include/linux/fs.h:2220 [inline]
 generic_file_read_iter+0x1067/0x1490 mm/filemap.c:2279
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x2df/0x470 fs/splice.c:313
 do_splice_to+0xc7/0x100 fs/splice.c:892
 splice_direct_to_actor+0x1b9/0x540 fs/splice.c:971
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20347 Comm: syz-executor.2 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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