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Tue, 28 Oct 2025 13:36:54 +0000 (UTC) Date: Tue, 28 Oct 2025 14:36:48 +0100 From: Borislav Petkov To: Ankur Arora Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, david@redhat.com, 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 Subject: Re: [PATCH v8 4/7] x86/mm: Simplify clear_page_* Message-ID: <20251028133648.GAaQDG8PfOwrSiHYuk@fat_crate.local> References: <20251027202109.678022-1-ankur.a.arora@oracle.com> <20251027202109.678022-5-ankur.a.arora@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251027202109.678022-5-ankur.a.arora@oracle.com> X-Stat-Signature: m1p6igz8tczse6sdrdiyhb97dohgtr5s X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7FCEA4001A X-HE-Tag: 1761658643-729025 X-HE-Meta: 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 DxKkpkJL INE2MVyrkwsFd1+QpSeVYUdNj8qDKXaFbTNIQM8u2IGmFkv4cHWq/1h472FRBDO9ohJO00IUDNra5LVoSUxdkbZVOwY9bV1IPFLEvx08q96PyBCcfoPQqVYOW4Zpy7y0rqzbKBl3sBySKRMxWGAbpkONYDyeL1f9cz6PvWGu8oyJK+glBT3K3IPvfD3FOu0lTrhizEE7VUCyNZRmx1YKq13Kc0/Jr6tKieDZ/0QVlgLzy1C4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Oct 27, 2025 at 01:21:06PM -0700, Ankur Arora wrote: > +/** > + * clear_page() - clear a page using a kernel virtual address. > + * @addr: address of kernel page > + * > + * Switch between three implementations of page clearing based on CPU > + * capabilities: > + * > + * - memzero_page_aligned_unrolled(): the oldest, slowest and universally So I don't see how a memzero_ name shows that it belongs to the clear_page "stack" of functions? clear_page_orig() kinda conveys better what this thing is. In any case, having "clear_page" somewhere there in the name should stay. > + * supported method. Zeroes via 8-byte MOV instructions unrolled 8x > + * to write a 64-byte cacheline in each loop iteration.. ^ one fullstop is enough. > + * > + * - "rep stosq": really old CPUs had crummy REP implementations. We spell all x86 insns in ALL CAPS. Like you've almost done. Also, it is REP; STOSQ with a ; Otherwise the idea for the cleanup makes sense. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette