==================================================================
BUG: KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

write to 0xffff8881013cb258 of 4 bytes by task 4989 on cpu 0:
 mb_free_blocks+0x323/0xb40 fs/ext4/mballoc.c:1833
 ext4_mb_release_inode_pa+0x2d6/0x540 fs/ext4/mballoc.c:4694
 ext4_discard_preallocations+0x7a8/0xb40 fs/ext4/mballoc.c:4958
 ext4_move_extents+0x5cc/0x2250 fs/ext4/move_extent.c:690
 __ext4_ioctl fs/ext4/ioctl.c:938 [inline]
 ext4_ioctl+0x12f4/0x1df0 fs/ext4/ioctl.c:1224
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881013cb258 of 4 bytes by task 4990 on cpu 1:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:834 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:811 [inline]
 mb_update_avg_fragment_size+0x161/0x260 fs/ext4/mballoc.c:859
 mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1993
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2014
 ext4_mb_measure_extent fs/ext4/mballoc.c:2086 [inline]
 ext4_mb_complex_scan_group+0x55d/0x850 fs/ext4/mballoc.c:2360
 ext4_mb_regular_allocator+0x1a22/0x2520 fs/ext4/mballoc.c:2759
 ext4_mb_new_blocks+0x74a/0x1fa0 fs/ext4/mballoc.c:5514
 ext4_new_meta_blocks+0x84/0x180 fs/ext4/balloc.c:693
 ext4_ext_grow_indepth fs/ext4/extents.c:1276 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1380 [inline]
 ext4_ext_insert_extent+0x9b3/0x2bc0 fs/ext4/extents.c:2054
 ext4_split_extent_at+0x6f2/0xb40 fs/ext4/extents.c:3208
 ext4_split_extent+0x134/0x2d0 fs/ext4/extents.c:3306
 ext4_split_convert_extents fs/ext4/extents.c:3665 [inline]
 ext4_ext_handle_unwritten_extents+0x1f4/0xaa0 fs/ext4/extents.c:3827
 ext4_ext_map_blocks+0x719/0x1f00 fs/ext4/extents.c:4119
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_iomap_alloc fs/ext4/inode.c:3426 [inline]
 ext4_iomap_begin+0x4a3/0x620 fs/ext4/inode.c:3476
 iomap_apply+0x8d/0x400 fs/iomap/apply.c:46
 __iomap_dio_rw+0x5af/0xad0 fs/iomap/direct-io.c:561
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:649
 ext4_dio_write_iter fs/ext4/file.c:568 [inline]
 ext4_file_write_iter+0xa4f/0x11d0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 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+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4990 Comm: syz-executor.3 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
syz-executor.3 (4990) used greatest stack depth: 8640 bytes left