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Mon, 07 Dec 2020 18:26:41 -0800 (PST) MIME-Version: 1.0 References: <20201130151838.11208-1-songmuchun@bytedance.com> <600fd7e2-70b4-810f-8d12-62cba80af80d@oracle.com> <20201207183814.GA3786@localhost.localdomain> In-Reply-To: <20201207183814.GA3786@localhost.localdomain> From: Muchun Song Date: Tue, 8 Dec 2020 10:26:05 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v7 00/15] Free some vmemmap pages of hugetlb page To: Oscar Salvador Cc: Mike Kravetz , Andrew Morton , Jonathan Corbet , dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, bp@alien8.de, mingo@redhat.com, Thomas Gleixner , pawan.kumar.gupta@linux.intel.com, mchehab+huawei@kernel.org, paulmck@kernel.org, viro@zeniv.linux.org.uk, Peter Zijlstra , luto@kernel.org, oneukum@suse.com, jroedel@suse.de, Matthew Wilcox , David Rientjes , Mina Almasry , Randy Dunlap , anshuman.khandual@arm.com, Michal Hocko , "Song Bao Hua (Barry Song)" , Xiongchun duan , LKML , Linux Memory Management List , linux-doc@vger.kernel.org, linux-fsdevel Content-Type: text/plain; charset="UTF-8" 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: On Tue, Dec 8, 2020 at 2:38 AM Oscar Salvador wrote: > > On Fri, Dec 04, 2020 at 11:39:31AM +0800, Muchun Song wrote: > > On Fri, Dec 4, 2020 at 7:49 AM Mike Kravetz wrote: > > > As previously mentioned, I feel qualified to review the hugetlb changes > > > and some other closely related changes. However, this patch set is > > > touching quite a few areas and I do not feel qualified to make authoritative > > > statements about them all. I too hope others will take a look. > > > > Agree. I also hope others can take a look at other modules(e.g. > > sparse-vmemmap, memory-hotplug). Thanks for everyone's efforts > > on this. > > I got sidetracked by some other stuff but I plan to continue reviewing > this series. Many thanks, Oscar. > > One thing that came to my mind is that if we do as David suggested in > patch#4, and we move it towards the end to actually __enable__ this > once all the infrastructure is there (unless hstate->nr_vmemmap_pages > differs from 0 we should not be doing any work AFAIK), we could also > move patch#6 to the end (right before the enablement), kill patch#7 > and only leave patch#13. > > The reason for that (killing patch#7 and leaving patch#13 only) > is that it does not make much sense to me to disable PMD-mapped vmemmap > depending on the CONFIG_HUGETLB_xxxxx as that is enabled by default > to replace that later by the boot kernel parameter. > It looks more natural to me to disable it when we introduce the kernel > boot parameter, before the actual enablement of the feature. Thanks for your suggestions. I agree with you. :) > > As I said, I plan to start the review again, but the order above would > make more sense to me. > > thanks > > -- > Oscar Salvador > SUSE L3 -- Yours, Muchun