syzbot

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BUG: KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order

write to 0xffff88810047131c of 4 bytes by task 9032 on cpu 0:
 mb_set_largest_free_order+0x159/0x330 fs/ext4/mballoc.c:1084
 mb_mark_used+0xac0/0xc50 fs/ext4/mballoc.c:1991
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2014
 ext4_mb_simple_scan_group+0x253/0x3a0 fs/ext4/mballoc.c:2292
 ext4_mb_regular_allocator+0x1974/0x2520 fs/ext4/mballoc.c:2754
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5514
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4712
 vfs_fallocate+0x463/0x660 fs/open.c:311
 file_ioctl fs/ioctl.c:497 [inline]
 do_vfs_ioctl+0x1322/0x1410 fs/ioctl.c:1048
 __do_sys_ioctl fs/ioctl.c:1067 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 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 0xffff88810047131c of 4 bytes by task 9034 on cpu 1:
 ext4_mb_good_group+0x30f/0x370 fs/ext4/mballoc.c:2451
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2528 [inline]
 ext4_mb_regular_allocator+0x1600/0x2520 fs/ext4/mballoc.c:2728
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5514
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4712
 vfs_fallocate+0x463/0x660 fs/open.c:311
 file_ioctl fs/ioctl.c:497 [inline]
 do_vfs_ioctl+0x1322/0x1410 fs/ioctl.c:1048
 __do_sys_ioctl fs/ioctl.c:1067 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 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: 0x0000000c -> 0x0000000b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9034 Comm: syz-executor.3 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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