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BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

write to 0xffff8881065f91b8 of 4 bytes by task 22 on cpu 0:
 ext4_ext_store_pblock fs/ext4/ext4_extents.h:255 [inline]
 ext4_ext_insert_extent+0x1235/0x2bc0 fs/ext4/extents.c:2116
 ext4_ext_map_blocks+0x167d/0x1f00 fs/ext4/extents.c:4262
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 mpage_map_one_extent+0x10d/0x360 fs/ext4/inode.c:2395
 mpage_map_and_submit_extent fs/ext4/inode.c:2448 [inline]
 ext4_writepages+0xc1a/0x1d10 fs/ext4/inode.c:2800
 do_writepages+0x7b/0x150 mm/page-writeback.c:2360
 __writeback_single_inode+0x80/0x440 fs/fs-writeback.c:1605
 writeback_sb_inodes+0x563/0xd10 fs/fs-writeback.c:1870
 wb_writeback+0x28e/0x700 fs/fs-writeback.c:2043
 wb_do_writeback+0x101/0x510 fs/fs-writeback.c:2188
 wb_workfn+0xc8/0x520 fs/fs-writeback.c:2229
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

read to 0xffff8881065f91b8 of 4 bytes by task 7890 on cpu 1:
 ext4_do_update_inode fs/ext4/inode.c:5109 [inline]
 ext4_mark_iloc_dirty+0xe2d/0x1750 fs/ext4/inode.c:5724
 __ext4_mark_inode_dirty+0x4db/0x5b0 fs/ext4/inode.c:5918
 ext4_dirty_inode+0x86/0xa0 fs/ext4/inode.c:5947
 __mark_inode_dirty+0x77/0x6c0 fs/fs-writeback.c:2412
 mark_inode_dirty include/linux/fs.h:2404 [inline]
 generic_write_end+0x157/0x180 fs/buffer.c:2198
 ext4_da_write_end+0x59b/0x730 fs/ext4/inode.c:3110
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3671
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0004ac00 -> 0x0004ad51

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7890 Comm: syz-executor.4 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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