[syzbot] memory leak in blk_iolatency_init

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a3fa7a101dcf Merge branches 'akpm' and 'akpm-hotfixes' (pa..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12b4a5b3300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9ee3a4c022ccbbca
dashboard link: https://syzkaller.appspot.com/bug?extid=01321b15cc98e6bf96d6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=148c170b300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01321b15cc98e6bf96d6@xxxxxxxxxxxxxxxxxxxxxxxxx

2021/09/09 22:14:31 executed programs: 444
BUG: memory leak
unreferenced object 0xffff888129acdb80 (size 96):
  comm "syz-executor.1", pid 12661, jiffies 4294962682 (age 15.220s)
  hex dump (first 32 bytes):
    20 47 c9 85 ff ff ff ff 20 d4 8e 29 81 88 ff ff   G...... ..)....
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff82264ec8>] kmalloc include/linux/slab.h:591 [inline]
    [<ffffffff82264ec8>] kzalloc include/linux/slab.h:721 [inline]
    [<ffffffff82264ec8>] blk_iolatency_init+0x28/0x190 block/blk-iolatency.c:724
    [<ffffffff8225b8c4>] blkcg_init_queue+0xb4/0x1c0 block/blk-cgroup.c:1185
    [<ffffffff822253da>] blk_alloc_queue+0x22a/0x2e0 block/blk-core.c:566
    [<ffffffff8223b175>] blk_mq_init_queue_data block/blk-mq.c:3100 [inline]
    [<ffffffff8223b175>] __blk_mq_alloc_disk+0x25/0xd0 block/blk-mq.c:3124
    [<ffffffff826a9303>] loop_add+0x1c3/0x360 drivers/block/loop.c:2344
    [<ffffffff826a966e>] loop_control_get_free drivers/block/loop.c:2501 [inline]
    [<ffffffff826a966e>] loop_control_ioctl+0x17e/0x2e0 drivers/block/loop.c:2516
    [<ffffffff81597eec>] vfs_ioctl fs/ioctl.c:51 [inline]
    [<ffffffff81597eec>] __do_sys_ioctl fs/ioctl.c:874 [inline]
    [<ffffffff81597eec>] __se_sys_ioctl fs/ioctl.c:860 [inline]
    [<ffffffff81597eec>] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860
    [<ffffffff843fa745>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<ffffffff843fa745>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
    [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae



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