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Wed, 13 Mar 2024 16:32:53 -0700 (PDT) Received: from [2620:0:1008:15:93dd:65bc:bbd0:d2ac] ([2620:0:1008:15:93dd:65bc:bbd0:d2ac]) by smtp.gmail.com with ESMTPSA id s14-20020a63dc0e000000b005df58c83e89sm185578pgg.84.2024.03.13.16.32.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Mar 2024 16:32:53 -0700 (PDT) Date: Wed, 13 Mar 2024 16:32:52 -0700 (PDT) From: David Rientjes To: Will Deacon cc: Nanyong Sun , Catalin Marinas , Matthew Wilcox , muchun.song@linux.dev, Andrew Morton , anshuman.khandual@arm.com, wangkefeng.wang@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yu Zhao , Yosry Ahmed , Sourav Panda Subject: Re: [PATCH v3 0/3] A Solution to Re-enable hugetlb vmemmap optimize In-Reply-To: <20240208131734.GA23428@willie-the-truck> Message-ID: References: <20240113094436.2506396-1-sunnanyong@huawei.com> <20240207111252.GA22167@willie-the-truck> <44075bc2-ac5f-ffcd-0d2f-4093351a6151@huawei.com> <20240208131734.GA23428@willie-the-truck> MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="2003064516-144154717-1710372487=:1424452" Content-ID: <35d77e60-41b9-7263-4bd3-47f07a148a86@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240313_163258_818502_8AB712E5 X-CRM114-Status: GOOD ( 15.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --2003064516-144154717-1710372487=:1424452 Content-Type: text/plain; CHARSET=UTF-8 Content-Transfer-Encoding: 8BIT Content-ID: <9e36df0a-b6e1-52a5-34af-6b5859d9248f@google.com> On Thu, 8 Feb 2024, Will Deacon wrote: > > How about take a new lock with irq disabled during BBM, like: > > > > +void vmemmap_update_pte(unsigned long addr, pte_t *ptep, pte_t pte) > > +{ > > +    spin_lock_irq(NEW_LOCK); > > +    pte_clear(&init_mm, addr, ptep); > > +    flush_tlb_kernel_range(addr, addr + PAGE_SIZE); > > +    set_pte_at(&init_mm, addr, ptep, pte); > > +    spin_unlock_irq(NEW_LOCK); > > +} > > I really think the only maintainable way to achieve this is to avoid the > possibility of a fault altogether. > > Will > > Nanyong, are you still actively working on making HVO possible on arm64? This would yield a substantial memory savings on hosts that are largely configured with hugetlbfs. In our case, the size of this hugetlbfs pool is actually never changed after boot, but it sounds from the thread that there was an idea to make HVO conditional on FEAT_BBM. Is this being pursued? If so, any testing help needed? --2003064516-144154717-1710372487=:1424452 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --2003064516-144154717-1710372487=:1424452--