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BUG: KCSAN: data-race in shmem_file_splice_read / shmem_setattr

write to 0xffff888107d965b0 of 8 bytes by task 26073 on cpu 1:
 i_size_write include/linux/fs.h:932 [inline]
 shmem_setattr+0x70d/0x840 mm/shmem.c:1186
 notify_change+0x866/0x8e0 fs/attr.c:499
 do_truncate+0x116/0x150 fs/open.c:66
 do_sys_ftruncate+0x2ba/0x3b0 fs/open.c:194
 __do_sys_ftruncate fs/open.c:205 [inline]
 __se_sys_ftruncate fs/open.c:203 [inline]
 __x64_sys_ftruncate+0x33/0x40 fs/open.c:203
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888107d965b0 of 8 bytes by task 26069 on cpu 0:
 i_size_read include/linux/fs.h:910 [inline]
 shmem_file_splice_read+0x145/0x600 mm/shmem.c:2933
 vfs_splice_read fs/splice.c:993 [inline]
 splice_direct_to_actor+0x28c/0x690 fs/splice.c:1069
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000420 -> 0x000000000000000d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26069 Comm: syz-executor.1 Tainted: G        W          6.6.0-rc1-syzkaller-00125-ge42bebf6db29 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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