cgroup: Unknown subsys name 'net'
=========================
WARNING: held lock freed!
5.16.0-rc2-next-20211129-syzkaller #0 Not tainted
-------------------------
syz-executor/6535 is freeing memory ffff8881472c5400-ffff8881472c55ff, with a lock still held there!
ffff8881472c5548 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove fs/kernfs/dir.c:1396 [inline]
ffff8881472c5548 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_destroy_root+0x81/0xb0 fs/kernfs/dir.c:964
2 locks held by syz-executor/6535:
 #0: ffffffff8bbc5d08 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock_and_drain_offline+0xa5/0x900 kernel/cgroup/cgroup.c:2998
 #1: ffff8881472c5548 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove fs/kernfs/dir.c:1396 [inline]
 #1: ffff8881472c5548 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_destroy_root+0x81/0xb0 fs/kernfs/dir.c:964

stack backtrace:
CPU: 0 PID: 6535 Comm: syz-executor Not tainted 5.16.0-rc2-next-20211129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_freed_lock_bug kernel/locking/lockdep.c:6388 [inline]
 debug_check_no_locks_freed.cold+0x9d/0xa9 kernel/locking/lockdep.c:6421
 slab_free_hook mm/slub.c:1695 [inline]
 slab_free_freelist_hook+0x73/0x1c0 mm/slub.c:1749
 slab_free mm/slub.c:3513 [inline]
 kfree+0xe0/0x430 mm/slub.c:4561
 kernfs_put.part.0+0x331/0x540 fs/kernfs/dir.c:548
 kernfs_put+0x42/0x50 fs/kernfs/dir.c:513
 __kernfs_remove+0x7a3/0xb20 fs/kernfs/dir.c:1382
 kernfs_remove fs/kernfs/dir.c:1397 [inline]
 kernfs_destroy_root+0x89/0xb0 fs/kernfs/dir.c:964
 cgroup_setup_root+0x3a6/0xad0 kernel/cgroup/cgroup.c:2077
 cgroup1_root_to_use kernel/cgroup/cgroup-v1.c:1194 [inline]
 cgroup1_get_tree+0xd33/0x1390 kernel/cgroup/cgroup-v1.c:1211
 vfs_get_tree+0x89/0x2f0 fs/super.c:1500
 do_new_mount fs/namespace.c:3004 [inline]
 path_mount+0x1320/0x1fa0 fs/namespace.c:3334
 do_mount fs/namespace.c:3347 [inline]
 __do_sys_mount fs/namespace.c:3555 [inline]
 __se_sys_mount fs/namespace.c:3532 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3532
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd22140301a
Code: 48 c7 c2 bc ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 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:00007ffc25f03ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc25f04038 RCX: 00007fd22140301a
RDX: 00007fd221465fd6 RSI: 00007fd22145c29a RDI: 00007fd22145ad71
RBP: 00007fd22145c29a R08: 00007fd22145c3f7 R09: 0000000000000026
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc25f03eb0
R13: 00007ffc25f04058 R14: 00007ffc25f03f80 R15: 00007fd22145c3f1
 </TASK>
==================================================================
BUG: KASAN: use-after-free in __up_write kernel/locking/rwsem.c:1318 [inline]
BUG: KASAN: use-after-free in up_write+0x3ac/0x470 kernel/locking/rwsem.c:1576
Read of size 8 at addr ffff8881472c5540 by task syz-executor/6535

CPU: 1 PID: 6535 Comm: syz-executor Not tainted 5.16.0-rc2-next-20211129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xa5/0x3ed mm/kasan/report.c:247
 __kasan_report mm/kasan/report.c:433 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:450
 __up_write kernel/locking/rwsem.c:1318 [inline]
 up_write+0x3ac/0x470 kernel/locking/rwsem.c:1576
 cgroup_setup_root+0x3a6/0xad0 kernel/cgroup/cgroup.c:2077
 cgroup1_root_to_use kernel/cgroup/cgroup-v1.c:1194 [inline]
 cgroup1_get_tree+0xd33/0x1390 kernel/cgroup/cgroup-v1.c:1211
 vfs_get_tree+0x89/0x2f0 fs/super.c:1500
 do_new_mount fs/namespace.c:3004 [inline]
 path_mount+0x1320/0x1fa0 fs/namespace.c:3334
 do_mount fs/namespace.c:3347 [inline]
 __do_sys_mount fs/namespace.c:3555 [inline]
 __se_sys_mount fs/namespace.c:3532 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3532
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd22140301a
Code: 48 c7 c2 bc ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 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:00007ffc25f03ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc25f04038 RCX: 00007fd22140301a
RDX: 00007fd221465fd6 RSI: 00007fd22145c29a RDI: 00007fd22145ad71
RBP: 00007fd22145c29a R08: 00007fd22145c3f7 R09: 0000000000000026
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc25f03eb0
R13: 00007ffc25f04058 R14: 00007ffc25f03f80 R15: 00007fd22145c3f1
 </TASK>

Allocated by task 6535:
 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:590 [inline]
 kzalloc include/linux/slab.h:724 [inline]
 kernfs_create_root+0x4c/0x410 fs/kernfs/dir.c:913
 cgroup_setup_root+0x243/0xad0 kernel/cgroup/cgroup.c:2018
 cgroup1_root_to_use kernel/cgroup/cgroup-v1.c:1194 [inline]
 cgroup1_get_tree+0xd33/0x1390 kernel/cgroup/cgroup-v1.c:1211
 vfs_get_tree+0x89/0x2f0 fs/super.c:1500
 do_new_mount fs/namespace.c:3004 [inline]
 path_mount+0x1320/0x1fa0 fs/namespace.c:3334
 do_mount fs/namespace.c:3347 [inline]
 __do_sys_mount fs/namespace.c:3555 [inline]
 __se_sys_mount fs/namespace.c:3532 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3532
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 6535:
 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0x103/0x170 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:1723 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1749
 slab_free mm/slub.c:3513 [inline]
 kfree+0xe0/0x430 mm/slub.c:4561
 kernfs_put.part.0+0x331/0x540 fs/kernfs/dir.c:548
 kernfs_put+0x42/0x50 fs/kernfs/dir.c:513
 __kernfs_remove+0x7a3/0xb20 fs/kernfs/dir.c:1382
 kernfs_remove fs/kernfs/dir.c:1397 [inline]
 kernfs_destroy_root+0x89/0xb0 fs/kernfs/dir.c:964
 cgroup_setup_root+0x3a6/0xad0 kernel/cgroup/cgroup.c:2077
 cgroup1_root_to_use kernel/cgroup/cgroup-v1.c:1194 [inline]
 cgroup1_get_tree+0xd33/0x1390 kernel/cgroup/cgroup-v1.c:1211
 vfs_get_tree+0x89/0x2f0 fs/super.c:1500
 do_new_mount fs/namespace.c:3004 [inline]
 path_mount+0x1320/0x1fa0 fs/namespace.c:3334
 do_mount fs/namespace.c:3347 [inline]
 __do_sys_mount fs/namespace.c:3555 [inline]
 __se_sys_mount fs/namespace.c:3532 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3532
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff8881472c5400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 320 bytes inside of
 512-byte region [ffff8881472c5400, ffff8881472c5600)
The buggy address belongs to the page:
page:ffffea00051cb100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1472c4
head:ffffea00051cb100 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000010200 0000000000000000 dead000000000001 ffff888010c41c80
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x52800(GFP_NOWAIT|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, ts 8095160016, free_ts 0
 prep_new_page mm/page_alloc.c:2433 [inline]
 get_page_from_freelist+0xa72/0x2f40 mm/page_alloc.c:4164
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5376
 alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2037
 alloc_pages+0x29f/0x300 mm/mempolicy.c:2187
 alloc_slab_page mm/slub.c:1793 [inline]
 allocate_slab mm/slub.c:1930 [inline]
 new_slab+0x261/0x460 mm/slub.c:1993
 ___slab_alloc+0x798/0xf30 mm/slub.c:3022
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109
 slab_alloc_node mm/slub.c:3200 [inline]
 kmem_cache_alloc_node_trace+0x116/0x310 mm/slub.c:3284
 kmalloc_node include/linux/slab.h:608 [inline]
 kzalloc_node include/linux/slab.h:735 [inline]
 iolatency_pd_alloc+0xb8/0x1b0 block/blk-iolatency.c:949
 blkcg_activate_policy block/blk-cgroup.c:1329 [inline]
 blkcg_activate_policy+0x232/0xc00 block/blk-cgroup.c:1302
 blk_iolatency_init+0x1aa/0x380 block/blk-iolatency.c:736
 blkcg_init_queue+0x194/0x780 block/blk-cgroup.c:1206
 blk_alloc_queue+0x44c/0x620 block/blk-core.c:494
 blk_mq_init_queue_data block/blk-mq.c:3875 [inline]
 __blk_mq_alloc_disk+0x4c/0x160 block/blk-mq.c:3899
 loop_add+0x339/0x900 drivers/block/loop.c:1988
 loop_init+0x1f4/0x216 drivers/block/loop.c:2243
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881472c5400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881472c5480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881472c5500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8881472c5580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881472c5600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================