From: David Hildenbrand <david@redhat.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
linux-mm@kvack.org
Cc: Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Liam.Howlett@oracle.com
Subject: Re: [PATCH 2/3] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone()
Date: Tue, 14 Oct 2025 09:16:32 +0200 [thread overview]
Message-ID: <93736a75-3fc5-47b0-8985-96e1b0b98b8a@redhat.com> (raw)
In-Reply-To: <4469b9c3-3656-44f5-897d-b024e030587f@huawei.com>
>>
>>> + if (prot_numa && pte_protnone(oldpte))
>>> + continue;
>>> +
>>> page = vm_normal_page(vma, addr, oldpte);
>>> if (page)
>>> folio = page_folio(page);
>>
>> I could have sworn we discussed that while fixing the prot_numa_skip()
>> fallout.
>
> I'm not follow the thread, but we found that vm_normal_page does
> introduce regression for mprotect benchmark(libMicro) with
> this vm_normal_page().
>
Right, I raised it here:
https://lkml.kernel.org/r/aa496798-5ac6-4cb0-bdc2-91515172e935@redhat.com
I questioned how relevant it would be in practice.
I'm surprised it shows up in a mprotect() benchmark: mprotect() itself
would never be able to set MM_CP_PROT_NUMA, so the code wold not
actually be executed.
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-10-14 7:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-13 12:15 [PATCH 0/3] mm: some optimizations for prot numa Kefeng Wang
2025-10-13 12:15 ` [PATCH 1/3] mm: mprotect: always skip dma pinned folio in prot_numa_skip() Kefeng Wang
2025-10-13 15:12 ` Sidhartha Kumar
2025-10-13 15:49 ` David Hildenbrand
2025-10-14 1:42 ` Lance Yang
2025-10-13 12:15 ` [PATCH 2/3] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone() Kefeng Wang
2025-10-13 15:22 ` Sidhartha Kumar
2025-10-13 15:53 ` David Hildenbrand
2025-10-14 6:06 ` Kefeng Wang
2025-10-14 7:16 ` David Hildenbrand [this message]
2025-10-14 8:02 ` Kefeng Wang
2025-10-14 8:56 ` David Hildenbrand
2025-10-14 9:19 ` Kefeng Wang
2025-10-13 12:15 ` [PATCH 3/3] mm: huge_memory: use prot_numa_skip() for pmd folio Kefeng Wang
2025-10-13 15:41 ` Sidhartha Kumar
2025-10-13 15:58 ` David Hildenbrand
2025-10-14 6:10 ` Kefeng Wang
2025-10-14 7:24 ` David Hildenbrand
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