linux-kernel - Re: [PATCH v1] drivers/base/memory: add memory block to memory group after registration succeeded

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Message-ID: <a457b70a-004c-e49a-26d2-c207c28bda98@redhat.com>
Date:   Tue, 1 Feb 2022 09:16:09 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v1] drivers/base/memory: add memory block to memory group
 after registration succeeded

On 01.02.22 02:01, Andrew Morton wrote:
> On Fri, 28 Jan 2022 15:45:40 +0100 David Hildenbrand <david@...hat.com> 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.
>>
> 
> I guess this has never been known to happen.  So I queued the fix for
> 5.18-rc1, cc:stable.

Triggering that registration error is fairly hard, usually we fail
memory hotplug because we fail to allocate the (largish) memmap. So I am
not aware that this BUG actually triggered.

-- 
Thanks,

David / dhildenb