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[2003:cb:c707:1600:a3ce:b459:ef57:7b93]) by smtp.gmail.com with ESMTPSA id o36-20020a05600c512400b003a5317f07b4sm1727479wms.37.2022.08.10.02.18.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Aug 2022 02:18:17 -0700 (PDT) Message-ID: Date: Wed, 10 Aug 2022 11:18:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW To: David Laight , "linux-kernel@vger.kernel.org" Cc: "linux-mm@kvack.org" , "stable@vger.kernel.org" , Linus Torvalds , Andrew Morton , Greg Kroah-Hartman , Axel Rasmussen , Nadav Amit , Peter Xu , Hugh Dickins , Andrea Arcangeli , Matthew Wilcox , Vlastimil Babka , John Hubbard , Jason Gunthorpe References: <20220809205640.70916-1-david@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FzplMLkC; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660123100; a=rsa-sha256; cv=none; b=tftCQZvgP+dDQpbPHyW76znN7Ql5u7NntWpBNttGaAeVRy/FDDg4SiW0RO3nSjiIrZDiVT Tjj3dkH4Ty212EvOobe7DoPWZtiwpcHdMB5wYynJ5yvhtCJ2/GKj7TY5dRJXRTehS/QChQ FIYjaGla1MICnDD0+U323jE1VasJR98= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660123100; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0uiFPFiP6Hf6PNS9QuyB3HMvVy2bvN3qOXGUpbbFgOo=; b=hDuYpqM5ExlYgM6++0ZbgN5bya1t9siGuolAdx0YNyAeZy96lXPelg0j1C8mguTT/gOKPG Roi8gKvSObEzzeE/ilTagW5q6cKsgfks5hzwPghTo6NJcznC//0ls/IvnhV+Cqx8Gcnwxo CJ4Q7eT5R3KtI1YlKDhdsvYwvyXzaBs= X-Stat-Signature: g3auxaz31qcfpi6aaip3t53pjz3kiqem X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 85B2D10017B Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FzplMLkC; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1660123100-307399 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 10.08.22 11:12, David Laight wrote: > From: David Hildenbrand >> Sent: 09 August 2022 21:57 > ... > > These two functions seem to contain a lot of the same tests. Yes, but after Linus and I discussed to not even reuse is_cow_mapping() but instead to spell it out, I refrained from factoring common checks out here to harm readability. [...] > > Perhaps only the initial call (common success path?) should > be inlined? > With the flags and vma tests being moved to an inline helper. Do we really care enough to hurt readability? I mean, most things here are simple bit checks, not expensive function calls. inline is only a hint to the compiler after all. Please correct me if I'm wrong. Now, I don't have any strong opinion, but I do want to make progress for this because -stable trees still need fixing and I'll be posting the reproducer on Monday. Thanks -- Thanks, David / dhildenb