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BUG: KCSAN: data-race in shmem_get_folio_gfp / shmem_setattr

write to 0xffff88812baf1e30 of 8 bytes by task 27945 on cpu 0:
 i_size_write include/linux/fs.h:932 [inline]
 shmem_setattr+0x6fb/0x830 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:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88812baf1e30 of 8 bytes by task 27922 on cpu 1:
 i_size_read include/linux/fs.h:910 [inline]
 shmem_get_folio_gfp+0x13f/0xb40 mm/shmem.c:1973
 shmem_get_folio mm/shmem.c:2134 [inline]
 shmem_file_splice_read+0x198/0x600 mm/shmem.c:2964
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x268/0x650 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x960 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1356 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1348
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x000000000000015a -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27922 Comm: syz-executor.3 Tainted: G        W          6.7.0-syzkaller-12829-g125514880ddd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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