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[217.140.101.70]) by mx.google.com with ESMTP id o15si377837ejm.144.2019.06.05.19.40.23 for ; Wed, 05 Jun 2019 19:40:23 -0700 (PDT) Received-SPF: pass (google.com: domain of anshuman.khandual@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of anshuman.khandual@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B927480D; Wed, 5 Jun 2019 19:40:22 -0700 (PDT) Received: from [10.162.43.122] (p8cg001049571a15.blr.arm.com [10.162.43.122]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 881D23F690; Wed, 5 Jun 2019 19:40:12 -0700 (PDT) Subject: Re: [RFC V2] mm: Generalize notify_page_fault() To: Matthew Wilcox , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, Andrew Morton , Michal Hocko , Mark Rutland , Christophe Leroy , Stephen Rothwell , Andrey Konovalov , Paul Mackerras , Russell King , Catalin Marinas , Will Deacon , Tony Luck , Fenghua Yu , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , "David S. Miller" , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Andy Lutomirski , Dave Hansen References: <1559630046-12940-1-git-send-email-anshuman.khandual@arm.com> <87sgsomg91.fsf@concordia.ellerman.id.au> <20190605112328.GB2025@bombadil.infradead.org> From: Anshuman Khandual Message-ID: Date: Thu, 6 Jun 2019 08:10:28 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190605112328.GB2025@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 06/05/2019 04:53 PM, Matthew Wilcox wrote: > On Wed, Jun 05, 2019 at 09:19:22PM +1000, Michael Ellerman wrote: >> Anshuman Khandual writes: >>> Similar notify_page_fault() definitions are being used by architectures >>> duplicating much of the same code. This attempts to unify them into a >>> single implementation, generalize it and then move it to a common place. >>> kprobes_built_in() can detect CONFIG_KPROBES, hence notify_page_fault() >>> need not be wrapped again within CONFIG_KPROBES. Trap number argument can >>> now contain upto an 'unsigned int' accommodating all possible platforms. >> ... >> >> You've changed several of the architectures from something like above, >> where it disables preemption around the call into the below: >> >> >> Which skips everything if we're preemptible. Is that an equivalent >> change? If so can you please explain why in more detail. > > See the discussion in v1 of this patch, which you were cc'd on. > > I agree the description here completely fails to mention why the change. > It should mention commit a980c0ef9f6d8c. I will update the commit message to include an explanation for this new preempt behavior in the generic definition.