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BUG: KCSAN: data-race in ext4_ext_try_to_merge_right / ext4_mark_iloc_dirty

write to 0xffff888106fdca70 of 2 bytes by task 590 on cpu 1:
 ext4_ext_try_to_merge_right+0x285/0x4c0 fs/ext4/extents.c:1772
 ext4_ext_try_to_merge+0x6b/0x310 fs/ext4/extents.c:1856
 ext4_convert_unwritten_extents_endio fs/ext4/extents.c:3728 [inline]
 ext4_ext_handle_unwritten_extents+0x67a/0xaa0 fs/ext4/extents.c:3856
 ext4_ext_map_blocks+0x719/0x1f00 fs/ext4/extents.c:4126
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_convert_unwritten_extents+0x15a/0x2c0 fs/ext4/extents.c:4767
 ext4_convert_unwritten_io_end_vec+0xa4/0x130 fs/ext4/extents.c:4806
 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+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 0xffff888106fdca70 of 4 bytes by task 13144 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:5109 [inline]
 ext4_mark_iloc_dirty+0xd15/0x1750 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+0x77/0x680 fs/fs-writeback.c:2395
 generic_update_time fs/inode.c:1772 [inline]
 update_time fs/inode.c:1785 [inline]
 file_update_time+0x3a4/0x3e0 fs/inode.c:2001
 ext4_page_mkwrite+0x11b/0xed0 fs/ext4/inode.c:6064
 do_page_mkwrite mm/memory.c:2773 [inline]
 wp_page_shared mm/memory.c:3106 [inline]
 do_wp_page+0x86c/0xba0 mm/memory.c:3207
 handle_pte_fault mm/memory.c:4438 [inline]
 __handle_mm_fault mm/memory.c:4555 [inline]
 handle_mm_fault+0xb28/0x1a60 mm/memory.c:4653
 do_user_addr_fault+0x609/0xc00 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568

value changed: 0x000000d0 -> 0x000000dc

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13144 Comm: syz-executor.0 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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