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BUG: KCSAN: data-race in generic_write_end / mpage_process_page_bufs

write to 0xffff888100493838 of 8 bytes by task 3803 on cpu 0:
 i_size_write include/linux/fs.h:932 [inline]
 generic_write_end+0x9f/0x240 fs/buffer.c:2304
 ext4_da_write_end+0x49e/0x700 fs/ext4/inode.c:2988
 generic_perform_write+0x26d/0x410 mm/filemap.c:3939
 ext4_buffered_write_iter+0x1f6/0x370 fs/ext4/file.c:299
 ext4_file_write_iter+0x283/0x1230
 call_write_iter include/linux/fs.h:1985 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888100493838 of 8 bytes by task 3807 on cpu 1:
 i_size_read include/linux/fs.h:910 [inline]
 mpage_process_page_bufs+0x34/0x5e0 fs/ext4/inode.c:1956
 mpage_prepare_extent_to_map+0x794/0xb90 fs/ext4/inode.c:2487
 ext4_do_writepages+0xa5e/0x21e0 fs/ext4/inode.c:2675
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2766
 do_writepages+0x1c5/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:393
 __filemap_fdatawrite_range mm/filemap.c:426 [inline]
 __filemap_fdatawrite mm/filemap.c:432 [inline]
 filemap_flush+0x95/0xc0 mm/filemap.c:459
 ext4_alloc_da_blocks+0x50/0x130 fs/ext4/inode.c:3033
 __ext4_ioctl fs/ext4/ioctl.c:1415 [inline]
 ext4_ioctl+0xff0/0x2db0 fs/ext4/ioctl.c:1618
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x000000000075b000 -> 0x000000000075c000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3807 Comm: syz-executor.0 Not tainted 6.5.0-syzkaller-01207-g1c59d383390f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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