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Shutemov" To: Chao Peng Cc: Sean Christopherson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: Re: [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Message-ID: <20220412192821.xliop57sblvjx4t4@box.shutemov.name> References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-5-chao.p.peng@linux.intel.com> <20220411153233.54ljmi7zgqovhgsn@box.shutemov.name> <20220412133925.GG8013@chaop.bj.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220412133925.GG8013@chaop.bj.intel.com> X-Stat-Signature: e8pe9tn44577aeweogjtb1po3kccph3z Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=shutemov-name.20210112.gappssmtp.com header.s=20210112 header.b=5r3BqAvH; dmarc=none; spf=none (imf25.hostedemail.com: domain of kirill@shutemov.name has no SPF policy when checking 209.85.208.181) smtp.mailfrom=kirill@shutemov.name X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: D0B41A0007 X-HE-Tag: 1649791611-246620 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, Apr 12, 2022 at 09:39:25PM +0800, Chao Peng wrote: > On Mon, Apr 11, 2022 at 06:32:33PM +0300, Kirill A. Shutemov wrote: > > On Thu, Apr 07, 2022 at 04:05:36PM +0000, Sean Christopherson wrote: > > > Hmm, shmem_writepage() already handles SHM_F_INACCESSIBLE by rejecting the swap, so > > > maybe it's just the page migration path that needs to be updated? > > > > My early version prevented migration with -ENOTSUPP for > > address_space_operations::migratepage(). > > > > What's wrong with that approach? > > I previously thought migratepage will not be called since we already > marked the pages as UNMOVABLE, sounds not correct? Do you mean missing __GFP_MOVABLE? I can be wrong, but I don't see that it direclty affects if the page is migratable. It is a hint to page allocator to group unmovable pages to separate page block and impove availablity of higher order pages this way. Page allocator tries to allocate unmovable pages from pages blocks that already have unmovable pages. -- Kirill A. Shutemov