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BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

write to 0xffff88810e786680 of 4 bytes by task 12496 on cpu 1:
 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+0x1597/0x1fd0 fs/ext4/extents.c:4259
 ext4_map_blocks+0x726/0xff0 fs/ext4/inode.c:638
 mpage_map_one_extent+0x10d/0x3a0 fs/ext4/inode.c:2397
 mpage_map_and_submit_extent fs/ext4/inode.c:2450 [inline]
 ext4_writepages+0xa51/0x1e70 fs/ext4/inode.c:2802
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:424
 filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:657
 __iomap_dio_rw+0x40a/0xa30 fs/iomap/direct-io.c:525
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:641
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x3bb/0x420 fs/ext4/file.c:128
 call_read_iter include/linux/fs.h:1971 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x7a6/0xe20 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810e786680 of 4 bytes by task 12460 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:5111 [inline]
 ext4_mark_iloc_dirty+0xd69/0x1700 fs/ext4/inode.c:5726
 __ext4_mark_inode_dirty+0x4db/0x5e0 fs/ext4/inode.c:5920
 ext4_dirty_inode+0x86/0xa0 fs/ext4/inode.c:5949
 __mark_inode_dirty+0x72/0x6f0 fs/fs-writeback.c:2274
 generic_update_time fs/inode.c:1766 [inline]
 update_time fs/inode.c:1779 [inline]
 touch_atime+0x1b3/0x2d0 fs/inode.c:1850
 file_accessed include/linux/fs.h:2319 [inline]
 filemap_read+0x74f/0x7b0 mm/filemap.c:2530
 generic_file_read_iter+0x82/0x410 mm/filemap.c:2609
 ext4_file_read_iter+0x2e0/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1971 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x7a6/0xe20 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12460 Comm: syz-executor.2 Not tainted 5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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