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Date:   Tue, 1 Feb 2022 13:11:13 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     David Hildenbrand <david@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH v1] drivers/base/memory: add memory block to memory group
 after registration succeeded
Message-ID: <YfkjYZK5EsYjg57Z@dhcp22.suse.cz>
References: <20220128144540.153902-1-david@redhat.com>
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On Fri 28-01-22 15:45:40, David Hildenbrand wrote:
> If register_memory() fails, we freed the memory block but already added
> the memory block to the group list, not good. Let's defer adding the
> block to the memory group to after registering the memory block device.
> 
> We do handle it properly during unregister_memory(), but that's not
> called when the registration fails.
> 
> Fixes: 028fc57a1c36 ("drivers/base/memory: introduce "memory groups" to logically group memory blocks")
> Cc: stable@vger.kernel.org # v5.15+
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!

> ---
>  drivers/base/memory.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 365cd4a7f239..60c38f9cf1a7 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -663,14 +663,16 @@ static int init_memory_block(unsigned long block_id, unsigned long state,
>  	mem->nr_vmemmap_pages = nr_vmemmap_pages;
>  	INIT_LIST_HEAD(&mem->group_next);
>  
> +	ret = register_memory(mem);
> +	if (ret)
> +		return ret;
> +
>  	if (group) {
>  		mem->group = group;
>  		list_add(&mem->group_next, &group->memory_blocks);
>  	}
>  
> -	ret = register_memory(mem);
> -
> -	return ret;
> +	return 0;
>  }
>  
>  static int add_memory_block(unsigned long base_section_nr)
> -- 
> 2.34.1

-- 
Michal Hocko
SUSE Labs