Path: csiph.com!1.us.feeder.erje.net!feeder.erje.net!2.us.feeder.erje.net!newsfeed.fsmpi.rwth-aachen.de!newsfeed.straub-nv.de!news.unit0.net!news.panservice.it!bofh.it!news.nic.it!robomod From: "Kirill A. Shutemov" Newsgroups: linux.kernel Subject: Re: [PATCH 2/2] mm/thp/pagecache/collapse: Free the pte page table on collapse for thp page cache. Date: Mon, 12 Dec 2016 22:10:02 +0100 Message-ID: References: X-Original-To: "Aneesh Kumar K.V" Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=UX4Og3N3EB+ptrVUeuqw+IYYCYxDnm4vYzXcF3I+Khc=; b=dbaT+bK39OVOq2eVR/cOnYADIAbfnh3Mc5pG5ar/q+NqTbPz/hXqYSu3i1KakExCD6 DNeGFRGskNY/jkGODP+UaJZiikBhmjSlrBlMR4GNo4xyPYkUXa202FVMg7KGpOydwpiH MR+838a6tuU6eD64VlPLF2cy3KU4KeJiOs09ainRpXY0vTfhjanhWlQrF3G2DyXaiS7A lq7Xze18R0yPd0Nfd8tLk+RvPB8IQg5XYGdkPKCXNirQ7UqCjl4r3XZeSvdSH0vt0g2V SdB54hujPidU8NTANBUXApVLSSyh6sEHr/luvbd6LPi8+0OcSDQTcZlEHd3GTfqOdjbc AxJQ== X-Google-Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=UX4Og3N3EB+ptrVUeuqw+IYYCYxDnm4vYzXcF3I+Khc=; b=Mc/4cUn19+MODrRg8JH1qzoICMx1+CkcgHpb0NCD15u+tuGSRPZjfu3tAzHCFw1JRU WPQ/S3psxYxD1wu05DnZG5HaefylAd9W6HEDat4GPRseM+Rh7/xBJ1dthAkMvQAvkH0L R1/sAqEd4HbMLF3nMioG193kZCxAilxyGeqBiDkemJLAMhdZrSBBugfpGh6jCpORXF5g K099q2HcKGA/95N4ge32RdxF/s3JGx8+aXWXzaLUf4wgQjyegxW9WPNJgcBERuwiMKXO 3WqupshapBSXPXHb2hY+1DwspIA9lY6xU4qKhARxWkG3irlgLEcWmw5e7mJoMcZqfFfg NAHA== X-Gm-Message-State: AKaTC01JJMk5TvF7zLT0EZkOV1Z1BD05LSfY4mlc8h8lV7EvFtHRbhKnXu6S3tSwIU7ASw== X-Received: by 10.28.141.143 with SMTP id p137mr18803368wmd.5.1481576531547; Mon, 12 Dec 2016 13:02:11 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 19 Organization: linux.* mail to news gateway X-Original-Cc: akpm@linux-foundation.org, "Kirill A . Shutemov" , mpe@ellerman.id.au, linux-mm@kvack.org, linux-kernel@vger.kernel.org X-Original-Date: Tue, 13 Dec 2016 00:02:09 +0300 X-Original-Message-ID: <20161212210209.GC10202@node.shutemov.name> X-Original-References: <20161212163428.6780-1-aneesh.kumar@linux.vnet.ibm.com> <20161212163428.6780-2-aneesh.kumar@linux.vnet.ibm.com> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1540659 On Mon, Dec 12, 2016 at 10:04:28PM +0530, Aneesh Kumar K.V wrote: > With THP page cache, when trying to build a huge page from regular pte pages, > we just clear the pmd entry. We will take another fault and at that point we > will find the huge page in the radix tree, thereby using the huge page to > complete the page fault > > The second fault path will allocate the needed pgtable_t page for archs like > ppc64. So no need to deposit the same in collapse path. Depositing them in > the collapse path resulting in a pgtable_t memory leak also giving errors like > "[ 2362.021762] BUG: non-zero nr_ptes on freeing mm: 3" > > Fixes:"mm: THP page cache support for ppc64" > > Signed-off-by: Aneesh Kumar K.V Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov