==================================================================
BUG: KCSAN: data-race in block_page_mkwrite / generic_write_end

write to 0xffff8881234bfbd8 of 8 bytes by task 25164 on cpu 0:
 i_size_write include/linux/fs.h:871 [inline]
 generic_write_end+0x98/0x230 fs/buffer.c:2183
 ext4_da_write_end+0x26c/0x620 fs/ext4/inode.c:3078
 generic_perform_write+0x264/0x3f0 mm/filemap.c:3780
 ext4_buffered_write_iter+0x222/0x330 fs/ext4/file.c:270
 ext4_file_write_iter+0x2e3/0x1210
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:868
 vfs_iter_write+0x4c/0x70 fs/read_write.c:909
 iter_file_splice_write+0x44a/0x7c0 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+0x345/0x660 fs/splice.c:891
 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:1327 [inline]
 __se_sys_sendfile64 fs/read_write.c:1313 [inline]
 __x64_sys_sendfile64+0x10c/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

read to 0xffff8881234bfbd8 of 8 bytes by task 25168 on cpu 1:
 i_size_read include/linux/fs.h:849 [inline]
 block_page_mkwrite+0xbb/0x4b0 fs/buffer.c:2508
 ext4_page_mkwrite+0x7c6/0xfa0 fs/ext4/inode.c:6091
 do_page_mkwrite mm/memory.c:2963 [inline]
 do_shared_fault mm/memory.c:4568 [inline]
 do_fault+0x749/0xb20 mm/memory.c:4636
 handle_pte_fault mm/memory.c:4895 [inline]
 __handle_mm_fault mm/memory.c:5034 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5132
 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+0x27/0x30
 copy_user_enhanced_fast_string+0xa/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
 ext4_file_read_iter+0x1e9/0x2a0
 call_read_iter include/linux/fs.h:2054 [inline]
 new_sync_read fs/read_write.c:401 [inline]
 vfs_read+0x5a5/0x6a0 fs/read_write.c:482
 ksys_read+0xe8/0x1a0 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/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

value changed: 0x0000000000010cf2 -> 0x0000000000010dd3

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25168 Comm: syz-executor.3 Not tainted 5.18.0-syzkaller-11712-g700170bf6b4d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================