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BUG: KCSAN: data-race in mb_mark_used / mb_update_avg_fragment_size

write to 0xffff8881018d7614 of 4 bytes by task 10978 on cpu 1:
 mb_mark_used+0x13b/0xc50 fs/ext4/mballoc.c:1947
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_find_by_goal+0x5c3/0x890
 ext4_mb_regular_allocator+0x11c/0x2520 fs/ext4/mballoc.c:2654
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5586
 ext4_ext_map_blocks+0x1579/0x1f10 fs/ext4/extents.c:4250
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:637
 mpage_map_one_extent+0x10d/0x360 fs/ext4/inode.c:2401
 mpage_map_and_submit_extent fs/ext4/inode.c:2454 [inline]
 ext4_writepages+0xc2a/0x1d30 fs/ext4/inode.c:2806
 do_writepages+0x25b/0x3a0 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:400 [inline]
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 filemap_write_and_wait_range+0x229/0x3b0 mm/filemap.c:704
 __iomap_dio_rw+0x472/0xfa0 fs/iomap/direct-io.c:540
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:649
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x21a/0x290 fs/ext4/file.c:128
 call_read_iter include/linux/fs.h:2157 [inline]
 generic_file_splice_read+0x22c/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+0x618/0xb90 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1300
 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

read to 0xffff8881018d7614 of 4 bytes by task 1784 on cpu 0:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:839 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:815 [inline]
 mb_update_avg_fragment_size+0x184/0x260 fs/ext4/mballoc.c:863
 mb_free_blocks+0x9e4/0xb40 fs/ext4/mballoc.c:1860
 ext4_free_blocks+0x1448/0x1b80 fs/ext4/mballoc.c:6061
 ext4_remove_blocks+0x61a/0x800 fs/ext4/extents.c:2506
 ext4_ext_rm_leaf+0x684/0xd40 fs/ext4/extents.c:2672
 ext4_ext_remove_space+0x8d6/0x1290 fs/ext4/extents.c:2920
 ext4_ext_truncate+0xfe/0x170 fs/ext4/extents.c:4382
 ext4_truncate+0x76e/0xa80 fs/ext4/inode.c:4268
 ext4_evict_inode+0xa54/0xdb0 fs/ext4/inode.c:287
 evict+0x1c8/0x3c0 fs/inode.c:586
 iput_final fs/inode.c:1662 [inline]
 iput+0x430/0x580 fs/inode.c:1688
 dentry_unlink_inode+0x273/0x290 fs/dcache.c:376
 d_delete+0x78/0xe0 fs/dcache.c:2505
 vfs_rmdir+0x2e6/0x300 fs/namei.c:3984
 do_rmdir+0x15d/0x310 fs/namei.c:4032
 __do_sys_rmdir fs/namei.c:4051 [inline]
 __se_sys_rmdir fs/namei.c:4049 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:4049
 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: 0x00007f9e -> 0x00007f7e

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1784 Comm: syz-executor.0 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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