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BUG: KCSAN: data-race in next_uptodate_page / shmem_write_end

write to 0xffff888138e1fd18 of 8 bytes by task 12526 on cpu 0:
 shmem_write_end+0x5d/0x3b0
 generic_perform_write+0x253/0x3d0
 __generic_file_write_iter+0xe6/0x290
 generic_file_write_iter+0x7d/0x1c0
 do_iter_write+0x418/0x700
 vfs_iter_write+0x50/0x70
 iter_file_splice_write+0x42b/0x7b0
 direct_splice_actor+0x84/0xa0
 splice_direct_to_actor+0x2ee/0x5f0
 do_splice_direct+0x104/0x180
 do_sendfile+0x3b8/0x950
 __x64_sys_sendfile64+0xbd/0x150
 do_syscall_64+0x41/0xc0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888138e1fd18 of 8 bytes by task 12527 on cpu 1:
 next_uptodate_page+0x47b/0x560
 filemap_map_pages+0xf9/0x830
 handle_mm_fault+0x1044/0x24d0
 exc_page_fault+0x45f/0x640
 asm_exc_page_fault+0x26/0x30
 copy_user_enhanced_fast_string+0xe/0x40
 _copy_from_user+0x7c/0xd0
 __get_filter+0xc7/0x210
 sk_attach_filter+0x1e/0xe0
 sk_setsockopt+0x16e1/0x1e10
 sock_setsockopt+0x3c/0x50
 __sys_setsockopt+0x177/0x230
 __x64_sys_setsockopt+0x66/0x80
 do_syscall_64+0x41/0xc0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000009dbc -> 0x0000000000009dda

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12527 Comm: syz-executor.1 Tainted: G        W          6.2.0-rc7-syzkaller-00002-gd2d11f342b17-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
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