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BUG: KCSAN: data-race in next_uptodate_page / shmem_write_end

write to 0xffff888109c88360 of 8 bytes by task 17570 on cpu 0:
 i_size_write include/linux/fs.h:871 [inline]
 shmem_write_end+0x60/0x3d0 mm/shmem.c:2505
 generic_perform_write+0x22a/0x3c0 mm/filemap.c:3667
 __generic_file_write_iter+0x161/0x300 mm/filemap.c:3783
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3815
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1319 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1311
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888109c88360 of 8 bytes by task 17580 on cpu 1:
 i_size_read include/linux/fs.h:849 [inline]
 next_uptodate_page+0x323/0x670 mm/filemap.c:3146
 first_map_page mm/filemap.c:3163 [inline]
 filemap_map_pages+0xe5/0x870 mm/filemap.c:3189
 do_fault_around mm/memory.c:4151 [inline]
 do_read_fault mm/memory.c:4166 [inline]
 do_fault mm/memory.c:4300 [inline]
 handle_pte_fault mm/memory.c:4558 [inline]
 __handle_mm_fault mm/memory.c:4693 [inline]
 handle_mm_fault+0xd83/0x1a50 mm/memory.c:4791
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
 copy_user_enhanced_fast_string+0xe/0x40 arch/x86/lib/copy_user_64.S:205
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0x7e/0xd0 lib/usercopy.c:16
 copy_from_user include/linux/uaccess.h:192 [inline]
 __get_filter+0xc7/0x210 net/core/filter.c:1495
 sk_attach_filter+0x21/0x260 net/core/filter.c:1526
 sock_setsockopt+0x12de/0x1d50 net/core/sock.c:1163
 __sys_setsockopt+0x14f/0x200 net/socket.c:2155
 __do_sys_setsockopt net/socket.c:2170 [inline]
 __se_sys_setsockopt net/socket.c:2167 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2167
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000000034d0 -> 0x00000000000034e4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17580 Comm: syz-executor.1 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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