On 18.06.2024 09:19, Xiu Jianfeng wrote:
> When CONFIG_DEBUG_LOCK_ALLOC is enabled, the following commands can
> trigger a bug,
>
> mount -t cgroup2 none /sys/fs/cgroup
> cd /sys/fs/cgroup
> echo "+hugetlb" > cgroup.subtree_control
>
> The log is as below:
>
> BUG: key ffff8880046d88d8 has not been registered!
> ------------[ cut here ]------------
> DEBUG_LOCKS_WARN_ON(1)
> WARNING: CPU: 3 PID: 226 at kernel/locking/lockdep.c:4945 lockdep_init_map_type+0x185/0x220
> Modules linked in:
> CPU: 3 PID: 226 Comm: bash Not tainted 6.10.0-rc4-next-20240617-g76db4c64526c #544
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> RIP: 0010:lockdep_init_map_type+0x185/0x220
> Code: 00 85 c0 0f 84 6c ff ff ff 8b 3d 6a d1 85 01 85 ff 0f 85 5e ff ff ff 48 c7 c6 21 99 4a 82 48 c7 c7 60 29 49 82 e8 3b 2e f5
> RSP: 0018:ffffc9000083fc30 EFLAGS: 00000282
> RAX: 0000000000000000 RBX: ffffffff828dd820 RCX: 0000000000000027
> RDX: ffff88803cd9cac8 RSI: 0000000000000001 RDI: ffff88803cd9cac0
> RBP: ffff88800674fbb0 R08: ffffffff828ce248 R09: 00000000ffffefff
> R10: ffffffff8285e260 R11: ffffffff828b8eb8 R12: ffff8880046d88d8
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880067281c0
> FS: 00007f68601ea740(0000) GS:ffff88803cd80000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005614f3ebc740 CR3: 000000000773a000 CR4: 00000000000006f0
> Call Trace:
> <TASK>
> ? __warn+0x77/0xd0
> ? lockdep_init_map_type+0x185/0x220
> ? report_bug+0x189/0x1a0
> ? handle_bug+0x3c/0x70
> ? exc_invalid_op+0x18/0x70
> ? asm_exc_invalid_op+0x1a/0x20
> ? lockdep_init_map_type+0x185/0x220
> __kernfs_create_file+0x79/0x100
> cgroup_addrm_files+0x163/0x380
> ? find_held_lock+0x2b/0x80
> ? find_held_lock+0x2b/0x80
> ? find_held_lock+0x2b/0x80
> css_populate_dir+0x73/0x180
> cgroup_apply_control_enable+0x12f/0x3a0
> cgroup_subtree_control_write+0x30b/0x440
> kernfs_fop_write_iter+0x13a/0x1f0
> vfs_write+0x341/0x450
> ksys_write+0x64/0xe0
> do_syscall_64+0x4b/0x110
> entry_SYSCALL_64_after_hwframe+0x76/0x7e
> RIP: 0033:0x7f68602d9833
> Code: 8b 15 61 26 0e 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 08
> RSP: 002b:00007fff9bbdf8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f68602d9833
> RDX: 0000000000000009 RSI: 00005614f3ebc740 RDI: 0000000000000001
> RBP: 00005614f3ebc740 R08: 000000000000000a R09: 0000000000000008
> R10: 00005614f3db6ba0 R11: 0000000000000246 R12: 0000000000000009
> R13: 00007f68603bd6a0 R14: 0000000000000009 R15: 00007f68603b8880
>
> For lockdep, there is a sanity check in lockdep_init_map_type(), the
> lock-class key must either have been allocated statically or must
> have been registered as a dynamic key. However the commit e18df2889ff9
> ("mm/hugetlb_cgroup: prepare cftypes based on template") has changed
> the cftypes from static allocated objects to dynamic allocated objects,
> so the cft->lockdep_key must be registered proactively.
>
> Fixes: e18df2889ff9 ("mm/hugetlb_cgroup: prepare cftypes based on template")
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-lkp/202406181046.8d8b2492-oliver.sang@xxxxxxxxx
> Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> v2: add bug log to commit message
> ---
> mm/hugetlb_cgroup.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index 2b899c4ae968..4ff238ba1250 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -836,6 +836,8 @@ hugetlb_cgroup_cfttypes_init(struct hstate *h, struct cftype *cft,
> cft->file_offset = MEMFILE_OFFSET0(offset) +
> MEMFILE_FIELD_SIZE(offset) * idx;
> }
> +
> + lockdep_register_key(&cft->lockdep_key);
> }
> }
>
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
