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Howlett" , Lorenzo Stoakes , Vlastimil Babka , Suren Baghdasaryan , Subject: Re: [PATCH v2 1/4] mm: mincore: use walk_page_range_vma() in do_mincore() Message-Id: <20260624193852.2a1ac8a187978e4baa75f47e@linux-foundation.org> In-Reply-To: References: <20260618092845.3905740-1-wangkefeng.wang@huawei.com> <20260618092845.3905740-2-wangkefeng.wang@huawei.com> <42e167b2-5676-45fd-8f3a-738d2f4f6623@huawei.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 046D720009 X-Stat-Signature: i84hrewqu3ugss7x8sm8efum1rnc4fi7 X-HE-Tag: 1782355133-629224 X-HE-Meta: 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 lFPdIQbG joPa95KTKqfTA++olU1uo9wGhpHd768Wq7QwtmysbICA/nL2srjSLEIPPHW6e/oR51cHlVbf2QF046OorERQLQI0lYmJXRVXUd3veYzPyhjzBhaRueuSS5wtDw6z8YDp9ehKOjX4tPed3DX8sc7n9GGh2OpRqHNhSCLbXFQlQaaJq/fkcHteNdD7TOum27C7OZWf5FBEEOx06eS/rBBeifaGLd8RXH8XMGKzA0VKVKeuXcyFyUYWXEeW9eRFuUGzssxeZcon8kCiJZ2RIMcOGyLFlVKMMhjfx+VFW8KCTKv9oDTVtigsLjMqeDPhMiXjhEYmgm4T+IWhHkOeNuhZ53LAShGRu85MDzLZvJMhJNG9bB8B0v6v83shQ1cz9TR7NJarA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 22 Jun 2026 11:23:11 +0800 Kefeng Wang wrote: > >>>> - err = walk_page_range(vma->vm_mm, addr, end, &mincore_walk_ops, vec); > >>>> + > >>>> + /* > >>>> + * walk_page_range_vma() does not call walk_page_test(), which > >>>> + * handles VM_PFNMAP VMA by invoking ->pte_hole() to skip the > >>>> + * page table walk. Without this check, PFNMAP PTEs would be > >>>> + * treated as present by mincore_pte_range(), changing the returned > >>>> + * residency status from the historical "not resident" to "resident". > >>>> + * Handle VM_PFNMAP explicitly to preserve the original behavior. > >>>> + */ > > > > I would rather we amend this comment to something like: > > > > /* mincore (historically) reports PFNMAP mappings as non-resident. */ > > > > because we don't need to explain internal differences in walk_page_range > > functions in a random comment in mincore. And perhaps attempt a separate > > Hope Andrew can fix the comments when pickup patches. I added this: --- a/mm/mincore.c~mm-mincore-use-walk_page_range_vma-in-do_mincore-fix +++ a/mm/mincore.c @@ -261,12 +261,7 @@ static long do_mincore(unsigned long add } /* - * walk_page_range_vma() does not call walk_page_test(), which - * handles VM_PFNMAP VMA by invoking ->pte_hole() to skip the - * page table walk. Without this check, PFNMAP PTEs would be - * treated as present by mincore_pte_range(), changing the returned - * residency status from the historical "not resident" to "resident". - * Handle VM_PFNMAP explicitly to preserve the original behavior. + * mincore historically reports PFNMAP mappings as non-resident. */ if (vma->vm_flags & VM_PFNMAP) { __mincore_unmapped_range(addr, end, vma, vec); _ Sashiko is OK with your patchset, but it might have found four(!) pre-existing issues: https://sashiko.dev/#/patchset/20260618092845.3905740-1-wangkefeng.wang@huawei.com