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BUG: KCSAN: data-race in shmem_getpage_gfp / shmem_setattr

write to 0xffff888138c021d8 of 8 bytes by task 17678 on cpu 0:
 i_size_write include/linux/fs.h:871 [inline]
 shmem_setattr+0x29c/0x410 mm/shmem.c:1100
 notify_change+0x8e6/0xa00 fs/attr.c:424
 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+0x46/0xb0

read to 0xffff888138c021d8 of 8 bytes by task 17676 on cpu 1:
 i_size_read include/linux/fs.h:849 [inline]
 shmem_getpage_gfp+0x1a3/0x1750 mm/shmem.c:1842
 shmem_getpage mm/shmem.c:149 [inline]
 shmem_file_read_iter+0x151/0x6a0 mm/shmem.c:2553
 call_read_iter include/linux/fs.h:2052 [inline]
 generic_file_splice_read+0x1de/0x2c0 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2ac/0x660 fs/splice.c:870
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1262
 __do_sys_sendfile64 fs/read_write.c:1321 [inline]
 __se_sys_sendfile64 fs/read_write.c:1313 [inline]
 __x64_sys_sendfile64+0xb9/0x150 fs/read_write.c:1313
 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+0x46/0xb0

value changed: 0x0000000000316f67 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17676 Comm: syz-executor.1 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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