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BUG: KCSAN: data-race in shmem_symlink / vfs_getattr_nosec

write to 0xffff8881209a56e0 of 8 bytes by task 15209 on cpu 1:
 shmem_symlink+0x2ea/0x450 mm/shmem.c:3188
 vfs_symlink+0x218/0x2d0 fs/namei.c:3959
 do_symlinkat+0xee/0x280 fs/namei.c:3986
 __do_sys_symlink fs/namei.c:4005 [inline]
 __se_sys_symlink fs/namei.c:4003 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4003
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881209a56e0 of 8 bytes by task 14182 on cpu 0:
 i_size_read include/linux/fs.h:854 [inline]
 generic_fillattr fs/stat.c:45 [inline]
 vfs_getattr_nosec+0x262/0x310 fs/stat.c:90
 vfs_getattr fs/stat.c:124 [inline]
 vfs_statx+0x148/0x2b0 fs/stat.c:206
 vfs_stat include/linux/fs.h:3173 [inline]
 __do_sys_newstat fs/stat.c:361 [inline]
 __se_sys_newstat+0x46/0x250 fs/stat.c:357
 __x64_sys_newstat+0x2d/0x40 fs/stat.c:357
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14182 Comm: systemd-udevd Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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