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Mon, 23 Jan 2023 23:34:37 -0800 (PST) Date: Wed, 25 Jan 2023 01:34:23 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Christoph Lameter Cc: Vlastimil Babka , Andrew Morton , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , Ingo Molnar , Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Dennis Zhou , Tejun Heo Subject: Re: [PATCH mm-unstable] lib/Kconfig.debug: do not enable DEBUG_PREEMPT by default Message-ID: References: <20230121033942.350387-1-42.hyeyoo@gmail.com> <86e68d3b-b029-5e82-5bbc-e0ccc2ae1d36@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: e5xf97bhyeo7m1ppbho1gk7j846q7qsz X-Rspamd-Queue-Id: 1587D140011 X-HE-Tag: 1674545680-875769 X-HE-Meta: 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 trlbQn5E 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 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 Mon, Jan 23, 2023 at 12:05:00PM +0100, Christoph Lameter wrote: > On Sat, 21 Jan 2023, Hyeonggon Yoo wrote: > > > Whew, I still get confused about who to Cc, thanks for adding them. > > and I also didn't include the percpu memory allocator maintainers, who may > > have opinion. let's add them too. > > Well looks ok to me. Thanks for looking at! > However, I thought most distro kernels disable PREEMPT anyways for > performance reasons? So DEBUG_PREEMPT should be off as well. I guess that > is why this has not been an issue so far. It depends on PREEMPTION, and PREEMPT_DYNAMIC ("Preemption behaviour defined on boot") selects PREEMPTION even if I end up using PREEMPT_VOLUNTARY. Not so many distros use DEBUG_PREEMPT, but I am occationally hit by this because debian and fedora enabled it :)