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BUG: KCSAN: data-race in block_page_mkwrite / generic_write_end

write to 0xffff88812c0f1178 of 8 bytes by task 9488 on cpu 1:
 i_size_write include/linux/fs.h:907 [inline]
 generic_write_end+0x99/0x230 fs/buffer.c:2183
 ext4_da_write_end+0x448/0x510 fs/ext4/inode.c:3068
 generic_perform_write+0x261/0x3f0 mm/filemap.c:3803
 ext4_buffered_write_iter+0x19d/0x290 fs/ext4/file.c:270
 ext4_file_write_iter+0x21a/0xd70
 call_write_iter include/linux/fs.h:2079 [inline]
 do_iter_readv_writev+0x27d/0x320 fs/read_write.c:726
 do_iter_write+0x192/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x43a/0x790 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+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1297
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x50 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812c0f1178 of 8 bytes by task 9490 on cpu 0:
 i_size_read include/linux/fs.h:885 [inline]
 block_page_mkwrite+0xbb/0x4c0 fs/buffer.c:2504
 ext4_page_mkwrite+0x664/0xdb0 fs/ext4/inode.c:6074
 do_page_mkwrite mm/memory.c:2885 [inline]
 do_shared_fault+0x223/0x7c0 mm/memory.c:4301
 do_fault mm/memory.c:4369 [inline]
 handle_pte_fault mm/memory.c:4623 [inline]
 __handle_mm_fault mm/memory.c:4759 [inline]
 handle_mm_fault+0x8a7/0xca0 mm/memory.c:4857
 do_user_addr_fault+0x617/0xb90 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1484 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1540
 asm_exc_page_fault+0x1e/0x30
 copy_user_enhanced_fast_string+0xe/0x40
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 copyout lib/iov_iter.c:155 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:226 [inline]
 __copy_page_to_iter lib/iov_iter.c:852 [inline]
 copy_page_to_iter+0x435/0x7c0 lib/iov_iter.c:880
 copy_folio_to_iter include/linux/uio.h:153 [inline]
 filemap_read+0xb2f/0xe10 mm/filemap.c:2736
 generic_file_read_iter+0x72/0x320 mm/filemap.c:2831
 call_read_iter include/linux/fs.h:2073 [inline]
 new_sync_read fs/read_write.c:401 [inline]
 vfs_read+0x5e2/0x6c0 fs/read_write.c:482
 ksys_read+0xd9/0x190 fs/read_write.c:620
 __do_sys_read fs/read_write.c:630 [inline]
 __se_sys_read fs/read_write.c:628 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x50 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000000636d2 -> 0x00000000000637b3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9490 Comm: syz-executor.4 Not tainted 5.17.0-syzkaller-13673-ge8b767f5e040-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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