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[2003:d8:2f1f:3f00:731a:f5e5:774e:d40c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3cf33fb9dbfsm20804803f8f.43.2025.09.02.13.16.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Sep 2025 13:16:42 -0700 (PDT) Message-ID: <643f5482-cd34-4534-8cd8-69f32482bc27@redhat.com> Date: Tue, 2 Sep 2025 22:16:40 +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 v6 11/15] mm: define clear_pages(), clear_user_pages() To: Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Cc: 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: <20250902080816.3715913-1-ankur.a.arora@oracle.com> <20250902080816.3715913-12-ankur.a.arora@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 02.09.25 10:08, Ankur Arora wrote: > Define fallback versions of clear_pages(), clear_user_pages(). > > In absence of architectural primitives, these just do straight clearing > sequentially. > > Signed-off-by: Ankur Arora > --- > include/linux/mm.h | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 1ae97a0b8ec7..b8c3f265b497 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3768,6 +3768,38 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, > unsigned int order) {} > #endif /* CONFIG_DEBUG_PAGEALLOC */ > > +#ifndef ARCH_PAGE_CONTIG_NR > +#define PAGE_CONTIG_NR 1 > +#else > +#define PAGE_CONTIG_NR ARCH_PAGE_CONTIG_NR > +#endif > + These likely don't belong into this aptch :) > +#ifndef clear_pages > +/* /** for proper kernel doc > + * clear_pages() - clear kernel page range. > + * @addr: start address of page range > + * @npages: number of pages > + * > + * Assumes that (@addr, +@npages) references a kernel region. > + * Like clear_page(), this does absolutely no exception handling. > + */ > +static inline void clear_pages(void *addr, unsigned int npages) > +{ > + for (int i = 0; i < npages; i++) > + clear_page(addr + i * PAGE_SIZE); If we know that we will clear at least one page (which we can document) do { clear_page(addr); addr += PAGE_SIZE; } while (--npages); Similarly for the case below. > +} > +#endif > + > +#ifndef clear_user_pages Can we add kernel doc here as well? > +static inline void clear_user_pages(void *addr, unsigned long vaddr, > + struct page *pg, unsigned int npages) > +{ > + for (int i = 0; i < npages; i++) > + clear_user_page(addr + i * PAGE_SIZE, > + vaddr + i * PAGE_SIZE, pg + i); > +} > +#endif > + > #ifdef __HAVE_ARCH_GATE_AREA > extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm); > extern int in_gate_area_no_mm(unsigned long addr); -- Cheers David / dhildenb