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Wed, 18 Nov 2020 03:28:00 +0000 (UTC) Received: from DGGEMM401-HUB.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4CbStQ72w2z55n3; Wed, 18 Nov 2020 11:27:42 +0800 (CST) Received: from dggemi711-chm.china.huawei.com (10.3.20.110) by DGGEMM401-HUB.china.huawei.com (10.3.20.209) with Microsoft SMTP Server (TLS) id 14.3.487.0; Wed, 18 Nov 2020 11:27:57 +0800 Received: from dggemi761-chm.china.huawei.com (10.1.198.147) by dggemi711-chm.china.huawei.com (10.3.20.110) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1913.5; Wed, 18 Nov 2020 11:27:56 +0800 Received: from dggemi761-chm.china.huawei.com ([10.9.49.202]) by dggemi761-chm.china.huawei.com ([10.9.49.202]) with mapi id 15.01.1913.007; Wed, 18 Nov 2020 11:27:56 +0800 From: "Song Bao Hua (Barry Song)" To: Oscar Salvador , Muchun Song CC: "corbet@lwn.net" , "mike.kravetz@oracle.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "x86@kernel.org" , "hpa@zytor.com" , "dave.hansen@linux.intel.com" , "luto@kernel.org" , "peterz@infradead.org" , "viro@zeniv.linux.org.uk" , "akpm@linux-foundation.org" , "paulmck@kernel.org" , "mchehab+huawei@kernel.org" , "pawan.kumar.gupta@linux.intel.com" , "rdunlap@infradead.org" , "oneukum@suse.com" , "anshuman.khandual@arm.com" , "jroedel@suse.de" , "almasrymina@google.com" , "rientjes@google.com" , "willy@infradead.org" , "mhocko@suse.com" , "duanxiongchun@bytedance.com" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" Subject: RE: [External] RE: [PATCH v4 00/21] Free some vmemmap pages of hugetlb page Thread-Topic: [External] RE: [PATCH v4 00/21] Free some vmemmap pages of hugetlb page Thread-Index: AQHWuaxO0H5megy+qEKBM1T+1aO5TKnMHhDQ//+HLICAAIXtUP//2OyAgAA21ICAAQU3oA== Date: Wed, 18 Nov 2020 03:27:56 +0000 Message-ID: References: <20201113105952.11638-1-songmuchun@bytedance.com> <349168819c1249d4bceea26597760b0a@hisilicon.com> <714ae7d701d446259ab269f14a030fe9@hisilicon.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.203.123] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-CFilter-Loop: Reflected 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: > -----Original Message----- > From: Oscar Salvador [mailto:osalvador@suse.de] > Sent: Wednesday, November 18, 2020 8:45 AM > To: Muchun Song > Cc: Song Bao Hua (Barry Song) ; > corbet@lwn.net; mike.kravetz@oracle.com; tglx@linutronix.de; > mingo@redhat.com; bp@alien8.de; x86@kernel.org; hpa@zytor.com; > dave.hansen@linux.intel.com; luto@kernel.org; peterz@infradead.org; > viro@zeniv.linux.org.uk; akpm@linux-foundation.org; paulmck@kernel.org; > mchehab+huawei@kernel.org; pawan.kumar.gupta@linux.intel.com; > rdunlap@infradead.org; oneukum@suse.com; anshuman.khandual@arm.com; > jroedel@suse.de; almasrymina@google.com; rientjes@google.com; > willy@infradead.org; mhocko@suse.com; duanxiongchun@bytedance.com; > linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org; linux-mm@kvack.o= rg; > linux-fsdevel@vger.kernel.org > Subject: Re: [External] RE: [PATCH v4 00/21] Free some vmemmap pages of > hugetlb page >=20 > On 2020-11-17 17:29, Muchun Song wrote: > > Now for the 2MB HugrTLB page, we only free 6 vmemmap pages. > > But your words woke me up. Maybe we really can free 7 vmemmap > > pages. In this case, we can see 8 of the 512 struct page structures > > has beed set PG_head flag. If we can adjust compound_head() > > slightly and make compound_head() return the real head struct > > page when the parameter is the tail struct page but with PG_head > > flag set. I will start an investigation and a test. >=20 > I would not overcomplicate things at this stage, but rather keep it > simple as the code is already tricky enough(without counting the LOC > thatvit adds). > We can always build on top later on in order to improve things. Yep. I am not expecting freeing tail page to be done at this stage. This co= uld be something in the todo list after the first patchset is solid. >=20 > -- > Oscar Salvador > SUSE L3 Thanks Barry