From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anshuman Khandual Date: Thu, 06 Jun 2019 02:52:28 +0000 Subject: Re: [RFC V2] mm: Generalize notify_page_fault() Message-Id: List-Id: References: <1559630046-12940-1-git-send-email-anshuman.khandual@arm.com> <87sgsomg91.fsf@concordia.ellerman.id.au> <20190605112328.GB2025@bombadil.infradead.org> In-Reply-To: <20190605112328.GB2025@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Matthew Wilcox , Michael Ellerman Cc: Mark Rutland , Michal Hocko , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Dave Hansen , Will Deacon , linux-mm@kvack.org, Paul Mackerras , sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato , x86@kernel.org, Russell King , Ingo Molnar , Fenghua Yu , Stephen Rothwell , Andrey Konovalov , Andy Lutomirski , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Tony Luck , Heiko Carstens , linux-kernel@vger.kernel.org, Martin Schwidefsky , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" 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.