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

write to 0xffff8881013821a0 of 8 bytes by task 3390 on cpu 0:
 i_size_write include/linux/fs.h:886 [inline]
 shmem_setattr+0x344/0x460 mm/shmem.c:1102
 notify_change+0x9f8/0xb20 fs/attr.c:420
 do_truncate fs/open.c:65 [inline]
 do_sys_ftruncate+0x317/0x420 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __x64_sys_ftruncate+0x2f/0x40 fs/open.c:202
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881013821a0 of 8 bytes by task 3382 on cpu 1:
 i_size_read include/linux/fs.h:864 [inline]
 shmem_file_read_iter+0x440/0x580 mm/shmem.c:2585
 call_read_iter include/linux/fs.h:2185 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0xb9/0x150 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000005d72 -> 0x0000000000000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3382 Comm: syz-executor.2 Tainted: G        W          6.1.0-rc2-syzkaller-00351-g91562cf99364-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
==================================================================