From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10660C433DF for ; Thu, 20 Aug 2020 21:40:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9B7AF21734 for ; Thu, 20 Aug 2020 21:40:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pzhc50Nf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B7AF21734 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 060808D0051; Thu, 20 Aug 2020 17:40:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 035E78D0050; Thu, 20 Aug 2020 17:40:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E66638D0051; Thu, 20 Aug 2020 17:40:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id D1EF08D0050 for ; Thu, 20 Aug 2020 17:40:07 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 91515180AD81F for ; Thu, 20 Aug 2020 21:40:07 +0000 (UTC) X-FDA: 77172265254.03.bread69_4a03d3427033 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id 4513728A4E8 for ; Thu, 20 Aug 2020 21:40:07 +0000 (UTC) X-HE-Tag: bread69_4a03d3427033 X-Filterd-Recvd-Size: 6051 Received: from mail-lf1-f65.google.com (mail-lf1-f65.google.com [209.85.167.65]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Thu, 20 Aug 2020 21:40:06 +0000 (UTC) Received: by mail-lf1-f65.google.com with SMTP id b11so1685773lfe.10 for ; Thu, 20 Aug 2020 14:40:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=JJqb9yiCkIQyfB6StyeV08QDa3nsuemRXnOPvduwv34=; b=pzhc50NfL269HtEIDzOejDw4jbSjCdJsy67LiTAsg2IJdfSpg18PX09n1HZM0XaGnT cRCztC9y7R8ptluylk7hApLFuQOCj/8uFUBrowMSNn+T8IFKrOLYv/1LJ5PyReBn4rsp l2HvJeFPPdKmG4w7S5bTfykTm5yZbzyRR0bn1JhdDWLzQCSy0tuyrsnd/juIUJfRcWmm BLYbueBLYUl2yYesuEo/CGtnGZjH1UiPDV0DA5SO/9/ehI15bakIN//IcsVoIF2WaOJt 5MwdCCAUqB8wvgFEonZcvC1JXNDSSUfP6TTsMFnVvuUjUymf6qFQXRjZboWcl1Bz0SuO Wzbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=JJqb9yiCkIQyfB6StyeV08QDa3nsuemRXnOPvduwv34=; b=bS2cpKvpVGd8HMdazCJvDT62WMj+NoE3ZhOWTHzaTpzv+G9XCrM2R6D/4wPyrqifPr WzH2FCPZfUkldJpmOKm6EaQIbQ4EKg1XH7KmcgR94ihVnaQ2Jp8DmloVz/PrnRty42Tt aMMhniJeCZnXCSaZ8jwb9yd3n80qbIbcXCnw/c1yd6wJxIiNNIciKCE+qcLDJgo1uSx4 XwkLmgsdFWxnUIQm2cx2hv9dwRzVZYvg9hGlKCKwWALtJ9RUbCZ2EtkD/TuuEqUzlPFH jYxYhbyAxIw6z9vgKOpR1XSPAw4HhIVAKWolXmL9D8aY9njFZQeMz3eKP6tN+XUU6ZVh NOvA== X-Gm-Message-State: AOAM531Lih/2jpudxVf4MFd6G+fMdoXFVgVH9pDhroOyftq4HRdCLRsP XlfQS4XoWCJQs+M8x8bzY6o= X-Google-Smtp-Source: ABdhPJwO0DvGLRK/14Dk650ZSbacdL1tNPMg7wwYmW1Cs2iJw0pNncmcJ7JnszhfCZVto3iXF2Uyug== X-Received: by 2002:a19:cc9:: with SMTP id 192mr172188lfm.61.1597959605144; Thu, 20 Aug 2020 14:40:05 -0700 (PDT) Received: from grain.localdomain ([5.18.103.226]) by smtp.gmail.com with ESMTPSA id y16sm676359ljg.21.2020.08.20.14.40.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2020 14:40:03 -0700 (PDT) Received: by grain.localdomain (Postfix, from userid 1000) id 368B21A0078; Fri, 21 Aug 2020 00:40:03 +0300 (MSK) Date: Fri, 21 Aug 2020 00:40:03 +0300 From: Cyrill Gorcunov To: Sumit Semwal Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexey Dobriyan , Jonathan Corbet , Mauro Carvalho Chehab , Kees Cook , Michal Hocko , Colin Cross , Alexey Gladkov , Matthew Wilcox , Jason Gunthorpe , "Kirill A . Shutemov" , Michel Lespinasse , Michal =?iso-8859-1?Q?Koutn=FD?= , Song Liu , Huang Ying , Vlastimil Babka , Yang Shi , chenqiwu , Mathieu Desnoyers , John Hubbard , Thomas Hellstrom , Mike Christie , Bart Van Assche , Amit Pundir , Thomas Gleixner , Christian Brauner , Daniel Jordan , Adrian Reber , Nicolas Viennot , Al Viro , Thomas Cedeno , linux-fsdevel@vger.kernel.org, Pekka Enberg , Dave Hansen , Peter Zijlstra , Ingo Molnar , Oleg Nesterov , "Eric W. Biederman" , Jan Glauber , John Stultz , Rob Landley , "Serge E. Hallyn" , David Rientjes , Hugh Dickins , Rik van Riel , Mel Gorman , Tang Chen , Robin Holt , Shaohua Li , Sasha Levin , Johannes Weiner , Minchan Kim Subject: Re: [PATCH v5 2/2] mm: add a field to store names for private anonymous memory Message-ID: <20200820214003.GR2074@grain> References: <20200819141650.7462-1-sumit.semwal@linaro.org> <20200819141650.7462-3-sumit.semwal@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200819141650.7462-3-sumit.semwal@linaro.org> User-Agent: Mutt/1.14.6 (2020-07-11) X-Rspamd-Queue-Id: 4513728A4E8 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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 Wed, Aug 19, 2020 at 07:46:50PM +0530, Sumit Semwal wrote: ... > Userspace can set the name for a region of memory by calling > prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name); > Setting the name to NULL clears it. > > The name is stored in a user pointer in the shared union in vm_area_struct > that points to a null terminated string inside the user process. vmas > that point to the same address and are otherwise mergeable will be merged, > but vmas that point to equivalent strings at different addresses will not > be merged. ... Guys, could you please enlighen me, I don't understand -- we pass some random user-space pointer and save it in vm_area_struct then in procfs we treat it as "string" and print out? What prevents me to put some crap here then unmap this pointer the kernel will cause page fault in procfs output (in best scenario)?