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

write to 0xffff88810177da94 of 4 bytes by task 19906 on cpu 0:
 mb_mark_used+0x13b/0xc50 fs/ext4/mballoc.c:1942
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2014
 ext4_mb_measure_extent fs/ext4/mballoc.c:2130 [inline]
 ext4_mb_complex_scan_group+0x349/0x850 fs/ext4/mballoc.c:2360
 ext4_mb_regular_allocator+0x1a22/0x2520 fs/ext4/mballoc.c:2759
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5514
 ext4_new_meta_blocks+0x84/0x180 fs/ext4/balloc.c:693
 ext4_alloc_branch fs/ext4/indirect.c:335 [inline]
 ext4_ind_map_blocks+0xaf7/0x1620 fs/ext4/indirect.c:626
 ext4_map_blocks+0x6d2/0xef0 fs/ext4/inode.c:640
 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+0xa04/0x11d0 fs/ext4/file.c:678
 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_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810177da94 of 4 bytes by task 19947 on cpu 1:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:835 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:811 [inline]
 mb_update_avg_fragment_size+0x184/0x260 fs/ext4/mballoc.c:859
 mb_free_blocks+0x9e4/0xb40 fs/ext4/mballoc.c:1856
 ext4_mb_release_inode_pa+0x2f1/0x560 fs/ext4/mballoc.c:4694
 ext4_discard_preallocations+0x7a8/0xb40 fs/ext4/mballoc.c:4958
 ext4_truncate+0x71e/0xa80 fs/ext4/inode.c:4259
 ext4_setattr+0xacc/0xec0 fs/ext4/inode.c:5504
 notify_change+0x8a3/0xa80 fs/attr.c:398
 do_truncate+0xe8/0x130 fs/open.c:64
 handle_truncate fs/namei.c:3017 [inline]
 do_open fs/namei.c:3365 [inline]
 path_openat+0x1a79/0x20b0 fs/namei.c:3494
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_openat fs/open.c:1219 [inline]
 __se_sys_openat fs/open.c:1214 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1214
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000003fc -> 0x000003fb

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19947 Comm: syz-executor.1 Not tainted 5.13.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
FAULT_INJECTION: forcing a failure.
name fail_page_alloc, interval 1, probability 0, space 0, times 0
CPU: 0 PID: 19947 Comm: syz-executor.1 Not tainted 5.13.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x19d lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 prepare_alloc_pages mm/page_alloc.c:4994 [inline]
 __alloc_pages+0x102/0x320 mm/page_alloc.c:5193
 alloc_pages+0x21d/0x310 mm/mempolicy.c:2272
 __page_cache_alloc+0x4d/0xf0 mm/filemap.c:1005
 pagecache_get_page+0x5f4/0x900 mm/filemap.c:1885
 grab_cache_page_write_begin+0x3f/0x70 mm/filemap.c:3610
 ext4_da_write_begin+0x305/0x820 fs/ext4/inode.c:2984
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3660
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_dio_write_iter fs/ext4/file.c:587 [inline]
 ext4_file_write_iter+0xd01/0x11d0 fs/ext4/file.c:678
 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_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f52aee60188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000000043408 RSI: 0000000020000200 RDI: 0000000000000005
RBP: 00007f52aee601d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffe8e569a4f R14: 00007f52aee60300 R15: 0000000000022000