syzbot

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BUG: KCSAN: data-race in atime_needs_update / setattr_copy

write to 0xffff8881304ee074 of 4 bytes by task 9068 on cpu 0:
 setattr_copy+0x5a/0x1c0 fs/attr.c:232
 shmem_setattr+0xb0/0x450 mm/shmem.c:1118
 notify_change+0x8a3/0xa80 fs/attr.c:398
 chown_common+0x23e/0x370 fs/open.c:682
 vfs_fchown fs/open.c:750 [inline]
 ksys_fchown+0xba/0x110 fs/open.c:761
 __do_sys_fchown fs/open.c:769 [inline]
 __se_sys_fchown fs/open.c:767 [inline]
 __x64_sys_fchown+0x3b/0x50 fs/open.c:767
 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 0xffff8881304ee074 of 4 bytes by task 9055 on cpu 1:
 i_uid_into_mnt include/linux/fs.h:1619 [inline]
 HAS_UNMAPPED_ID include/linux/fs.h:2253 [inline]
 atime_needs_update+0x58/0x390 fs/inode.c:1808
 touch_atime+0x54/0x240 fs/inode.c:1838
 file_accessed include/linux/fs.h:2455 [inline]
 shmem_file_read_iter+0x519/0x5d0 mm/shmem.c:2639
 call_read_iter include/linux/fs.h:2108 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 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:1319 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xa9/0x130 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: 0x00000000 -> 0x0000ee00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9055 Comm: syz-executor.5 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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