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BUG: KCSAN: data-race in block_page_mkwrite / generic_write_end

write to 0xffff8881360c9bd8 of 8 bytes by task 15047 on cpu 0:
 i_size_write include/linux/fs.h:878 [inline]
 generic_write_end+0x98/0x230 fs/buffer.c:2183
 ext4_da_write_end+0x446/0x510 fs/ext4/inode.c:3068
 generic_perform_write+0x26a/0x3f0 mm/filemap.c:3798
 ext4_buffered_write_iter+0x199/0x280 fs/ext4/file.c:270
 ext4_file_write_iter+0x211/0xdf0
 call_write_iter include/linux/fs.h:2050 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x71c/0x890 fs/read_write.c:591
 ksys_write+0xe8/0x1a0 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x44/0xae

read to 0xffff8881360c9bd8 of 8 bytes by task 15048 on cpu 1:
 i_size_read include/linux/fs.h:856 [inline]
 block_page_mkwrite+0xbb/0x4b0 fs/buffer.c:2503
 ext4_page_mkwrite+0x664/0xd20 fs/ext4/inode.c:6074
 do_page_mkwrite mm/memory.c:2885 [inline]
 wp_page_shared+0x277/0x5e0 mm/memory.c:3208
 do_wp_page+0x67e/0xd00 mm/memory.c:3325
 handle_pte_fault mm/memory.c:4645 [inline]
 __handle_mm_fault mm/memory.c:4763 [inline]
 handle_mm_fault+0x897/0xa40 mm/memory.c:4861
 do_user_addr_fault+0x4cd/0x940 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1484 [inline]
 exc_page_fault+0x60/0x160 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+0x423/0x7b0 lib/iov_iter.c:880
 copy_folio_to_iter include/linux/uio.h:153 [inline]
 filemap_read+0x10b2/0x1400 mm/filemap.c:2730
 generic_file_read_iter+0x72/0x320 mm/filemap.c:2825
 do_iter_readv_writev+0x27b/0x300
 do_iter_read+0x16f/0x5d0 fs/read_write.c:787
 vfs_readv fs/read_write.c:907 [inline]
 do_preadv+0x159/0x230 fs/read_write.c:999
 __do_sys_preadv fs/read_write.c:1049 [inline]
 __se_sys_preadv fs/read_write.c:1044 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1044
 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+0x44/0xae

value changed: 0x00000000000df000 -> 0x00000000000e3000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15048 Comm: syz-executor.4 Not tainted 5.18.0-rc3-syzkaller-00060-g59f0c2447e25-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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