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[80.187.80.144]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-40fb72fb711sm21683292f8f.11.2025.09.30.02.44.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Sep 2025 02:44:19 -0700 (PDT) Message-ID: Date: Tue, 30 Sep 2025 11:44:15 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 11/16] mm/highmem: introduce clear_user_highpages() To: Ankur Arora Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, mjguzik@gmail.com, luto@kernel.org, peterz@infradead.org, acme@kernel.org, namhyung@kernel.org, tglx@linutronix.de, willy@infradead.org, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com References: <20250917152418.4077386-1-ankur.a.arora@oracle.com> <20250917152418.4077386-12-ankur.a.arora@oracle.com> <6626d497-4c27-4263-9be1-1c05d2672019@redhat.com> <87ecrwewn3.fsf@oracle.com> <4e061f4f-cd57-4df4-a001-9eba80d1ded9@redhat.com> <877bxnayrc.fsf@oracle.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 25.09.25 07:26, Ankur Arora wrote: > > David Hildenbrand writes: > >> On 23.09.25 22:34, Ankur Arora wrote: >>> David Hildenbrand writes: >>> >>>> On 17.09.25 17:24, Ankur Arora wrote: >>>>> Define clear_user_highpages() which clears pages sequentially using >>>>> the single page variant. >>>>> With !CONFIG_HIGHMEM, pages are contiguous so use the range clearing >>>>> primitive clear_user_pages(). >>>>> Signed-off-by: Ankur Arora >>>>> --- >>>>> include/linux/highmem.h | 18 ++++++++++++++++++ >>>>> 1 file changed, 18 insertions(+) >>>>> diff --git a/include/linux/highmem.h b/include/linux/highmem.h >>>>> index 6234f316468c..ed609987e24d 100644 >>>>> --- a/include/linux/highmem.h >>>>> +++ b/include/linux/highmem.h >>>>> @@ -207,6 +207,24 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr) >>>>> } >>>>> #endif >>>>> +#ifndef clear_user_highpages >>>> >>>> Maybe we can add a simple kernel doc that points at the doc of clear_user_pages, >>>> but makes it clear that this for pages that might reside in highmem. >>> Didn't add one because clear_user_highpage() didn't have one. Will add >>> for both. >>> >> >> Doesn't have to be excessive. But even I have to keep reminding myself when to >> use clear_page(), clear_user_page(), clear_user_highpage() ... > > And now all the multi-page variants. Really motivates the removal of > the HIGHMEM stuff. :) I'm afraid it will stick around for a couple of years to come. -- Cheers David / dhildenb