From: Doug Berger <opendmb@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Oscar Salvador <osalvador@suse.de>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] mm/hugetlb: correct demote page offset logic
Date: Wed, 14 Sep 2022 14:49:20 -0700 [thread overview]
Message-ID: <efd8008a-6b81-ff4c-f0bd-4f957f00295e@gmail.com> (raw)
In-Reply-To: <20220914134927.16c229ccdc1a6b9da5d698c3@linux-foundation.org>
On 9/14/2022 1:49 PM, Andrew Morton wrote:
> On Wed, 14 Sep 2022 12:09:17 -0700 Doug Berger <opendmb@gmail.com> wrote:
>
>> With gigantic pages it may not be true that struct page structures
>> are contiguous across the entire gigantic page. The nth_page macro
>> is used here in place of direct pointer arithmetic to correct for
>> this.
>
> What were the user-visible runtime effects of this bug?
As Mike said this would only conceptually be a problem for systems with
CONFIG_SPARSEMEM && !CONFIG_SPARSEMEM_VMEMMAP, and could cause kernel
address exceptions or memory corruption with unpredictable side effects.
However, I am unaware of a system other than perhaps the PS3 that uses
the classic sparse addressing, so the odds of such a system also using
gigantic hugetlbfs pages that it wants to demote is likely quite small.
Thanks,
-Doug
next prev parent reply other threads:[~2022-09-14 21:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-14 19:09 [PATCH] mm/hugetlb: correct demote page offset logic Doug Berger
2022-09-14 20:49 ` Andrew Morton
2022-09-14 21:49 ` Doug Berger [this message]
2022-09-14 21:18 ` Mike Kravetz
2022-09-15 2:49 ` Anshuman Khandual
2022-09-15 4:04 ` Anshuman Khandual
2022-09-15 4:24 ` Oscar Salvador
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