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BUG: KCSAN: data-race in atime_needs_update / fat_truncate_time

read to 0xffff8881250c6120 of 8 bytes by task 13258 on cpu 0:
 relatime_need_update fs/inode.c:1628 [inline]
 atime_needs_update+0x1f7/0x360 fs/inode.c:1721
 touch_atime+0x63/0x190 fs/inode.c:1736
 file_accessed include/linux/fs.h:2209 [inline]
 generic_file_buffered_read mm/filemap.c:2258 [inline]
 generic_file_read_iter+0x116e/0x1440 mm/filemap.c:2324
 call_read_iter include/linux/fs.h:1896 [inline]
 generic_file_splice_read+0x35c/0x500 fs/splice.c:313
 do_splice_to+0xf2/0x130 fs/splice.c:892
 splice_direct_to_actor+0x1b6/0x540 fs/splice.c:971
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8881250c6120 of 8 bytes by task 13255 on cpu 1:
 fat_truncate_time+0x145/0x2e0 fs/fat/misc.c:307
 fat_update_time fs/fat/misc.c:330 [inline]
 fat_update_time+0x75/0x1c0 fs/fat/misc.c:322
 update_time fs/inode.c:1683 [inline]
 touch_atime+0x172/0x190 fs/inode.c:1754
 file_accessed include/linux/fs.h:2209 [inline]
 generic_file_buffered_read mm/filemap.c:2258 [inline]
 generic_file_read_iter+0x116e/0x1440 mm/filemap.c:2324
 call_read_iter include/linux/fs.h:1896 [inline]
 generic_file_splice_read+0x35c/0x500 fs/splice.c:313
 do_splice_to+0xf2/0x130 fs/splice.c:892
 splice_direct_to_actor+0x1b6/0x540 fs/splice.c:971
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13255 Comm: syz-executor.0 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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