linux-kernel - Re: [PATCH] mm/memory_hotplug: fix kfree() of bootmem memory

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Message-ID: <6d4ab70e-b944-5f7d-e9a3-979ac66c70f7@redhat.com>
Date:   Mon, 7 Feb 2022 15:33:34 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Miaohe Lin <linmiaohe@...wei.com>, akpm@...ux-foundation.org
Cc:     isimatu.yasuaki@...fujitsu.com, toshi.kani@...com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/memory_hotplug: fix kfree() of bootmem memory

On 07.02.22 14:56, Miaohe Lin wrote:
> We can't use kfree() to release the resource as it might come from bootmem.
> Use release_mem_region() instead.

How can this happen? release_mem_region() is called either from
__add_memory() or from add_memory_driver_managed(), where we allocated
the region via register_memory_resource(). Both functions shouldn't ever
be called before the buddy is up an running.

Do you have a backtrace of an actual instance of this issue? Or was this
identified as possibly broken by code inspection?

-- 
Thanks,

David / dhildenb