Path: csiph.com!eternal-september.org!feeder.eternal-september.org!aioe.org!news.servidellagleba.it!bofh.it!news.nic.it!robomod From: Borislav Petkov Newsgroups: linux.kernel Subject: Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Date: Wed, 21 Jun 2017 19:50:02 +0200 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 30 Organization: linux.* mail to news gateway X-Original-Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Nadav Amit , Rik van Riel , Dave Hansen , Arjan van de Ven , Peter Zijlstra X-Original-Date: Wed, 21 Jun 2017 19:43:20 +0200 X-Original-Message-ID: <20170621174320.gouuexwzoau6pjnj@pd.tnic> X-Original-References: X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1671853 On Tue, Jun 20, 2017 at 10:22:10PM -0700, Andy Lutomirski wrote: > - * The x86 doesn't have a mmu context, but > - * we put the segment information here. > + * x86 has arch-specific MMU state beyond what lives in mm_struct. > */ > typedef struct { > + /* > + * ctx_id uniquely identifies this mm_struct. A ctx_id will never > + * be reused, and zero is not a valid ctx_id. > + */ > + u64 ctx_id; > + > + /* > + * Any code that needs to do any sort of TLB flushing for this > + * mm will first make its changes to the page tables, then > + * increment tlb_gen, then flush. This lets the low-level > + * flushing code keep track of what needs flushing. > + * > + * This is not used on Xen PV. > + */ > + atomic64_t tlb_gen; Btw, can this just be a 4-byte int instead? I.e., simply atomic_t. I mean, it should be enough for all the TLB generations in flight, no? -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.