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BUG: KCSAN: data-race in shmem_reserve_inode / shmem_statfs

write to 0xffff888105f6b0f8 of 8 bytes by task 1183 on cpu 0:
 shmem_reserve_inode+0xb5/0x320 syzkaller/managers/upstream-kcsan-gce/kernel/mm/shmem.c:287
 shmem_get_inode+0x56/0x440 syzkaller/managers/upstream-kcsan-gce/kernel/mm/shmem.c:2300
 shmem_mknod+0x3b/0x170 syzkaller/managers/upstream-kcsan-gce/kernel/mm/shmem.c:2925
 shmem_create+0x27/0x30 syzkaller/managers/upstream-kcsan-gce/kernel/mm/shmem.c:2985
 lookup_open syzkaller/managers/upstream-kcsan-gce/kernel/fs/namei.c:3106 [inline]
 open_last_lookups syzkaller/managers/upstream-kcsan-gce/kernel/fs/namei.c:3180 [inline]
 path_openat+0xcb4/0x20a0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/namei.c:3368
 do_filp_open+0xbd/0x1d0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/namei.c:3398
 do_sys_openat2+0xa3/0x250 syzkaller/managers/upstream-kcsan-gce/kernel/fs/open.c:1172
 do_sys_open syzkaller/managers/upstream-kcsan-gce/kernel/fs/open.c:1188 [inline]
 __do_sys_open syzkaller/managers/upstream-kcsan-gce/kernel/fs/open.c:1196 [inline]
 __se_sys_open syzkaller/managers/upstream-kcsan-gce/kernel/fs/open.c:1192 [inline]
 __x64_sys_open+0xe2/0x110 syzkaller/managers/upstream-kcsan-gce/kernel/fs/open.c:1192
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888105f6b0f8 of 8 bytes by task 4883 on cpu 1:
 shmem_statfs+0x10b/0x130 syzkaller/managers/upstream-kcsan-gce/kernel/mm/shmem.c:2910
 statfs_by_dentry syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:66 [inline]
 vfs_statfs+0xb7/0x1c0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:90
 fd_statfs syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:120 [inline]
 __do_sys_fstatfs syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:216 [inline]
 __se_sys_fstatfs syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:213 [inline]
 __x64_sys_fstatfs+0x6c/0x130 syzkaller/managers/upstream-kcsan-gce/kernel/fs/statfs.c:213
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4883 Comm: systemd-journal Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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