==================================================================
BUG: KCSAN: data-race in shmem_file_read_iter / shmem_setattr

write to 0xffff888104067ab8 of 8 bytes by task 29344 on cpu 0:
 i_size_write include/linux/fs.h:916 [inline]
 shmem_setattr+0x299/0x450 mm/shmem.c:1108
 notify_change+0x8a3/0xac0 fs/attr.c:410
 do_truncate fs/open.c:64 [inline]
 do_sys_ftruncate+0x2ea/0x3a0 fs/open.c:192
 __do_sys_ftruncate fs/open.c:203 [inline]
 __se_sys_ftruncate fs/open.c:201 [inline]
 __x64_sys_ftruncate+0x2f/0x40 fs/open.c:201
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888104067ab8 of 8 bytes by task 29338 on cpu 1:
 i_size_read include/linux/fs.h:894 [inline]
 shmem_file_read_iter+0x22a/0x5d0 mm/shmem.c:2563
 call_read_iter include/linux/fs.h:2157 [inline]
 generic_file_splice_read+0x24f/0x330 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+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1308 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0xb9/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000315 -> 0x0000000000000007

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29338 Comm: syz-executor.1 Tainted: G        W         5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================