syzbot

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BUG: KCSAN: data-race in ext4_ext_try_to_merge / ext4_mark_iloc_dirty

write to 0xffff888105eca924 of 2 bytes by task 57 on cpu 1:
 ext4_ext_try_to_merge_up fs/ext4/extents.c:1835 [inline]
 ext4_ext_try_to_merge+0x2af/0x310 fs/ext4/extents.c:1865
 ext4_convert_unwritten_extents_endio fs/ext4/extents.c:3733 [inline]
 ext4_ext_handle_unwritten_extents+0x680/0xa90 fs/ext4/extents.c:3861
 ext4_ext_map_blocks+0x777/0x1ff0 fs/ext4/extents.c:4131
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 ext4_convert_unwritten_extents+0x17a/0x2d0 fs/ext4/extents.c:4773
 ext4_convert_unwritten_io_end_vec+0xa4/0x130 fs/ext4/extents.c:4812
 ext4_end_io_end fs/ext4/page-io.c:184 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:257 [inline]
 ext4_end_io_rsv_work+0x198/0x360 fs/ext4/page-io.c:271
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffff888105eca924 of 4 bytes by task 2762 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:5117 [inline]
 ext4_mark_iloc_dirty+0xc7d/0x1700 fs/ext4/inode.c:5741
 __ext4_mark_inode_dirty+0x4ec/0x5c0 fs/ext4/inode.c:5937
 ext4_write_end+0x3f7/0x800 fs/ext4/inode.c:1324
 ext4_da_write_end+0x93/0x730 fs/ext4/inode.c:3085
 generic_perform_write+0x251/0x3e0 mm/filemap.c:3781
 ext4_buffered_write_iter+0x309/0x400 fs/ext4/file.c:269
 ext4_file_write_iter+0x2f4/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x79c/0x8d0 fs/read_write.c:594
 ksys_write+0xd9/0x190 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00010004 -> 0x00000154

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2762 Comm: syz-executor.5 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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