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[109.81.88.1]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aac0e82f15dsm35600466b.23.2024.12.18.23.27.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Dec 2024 23:27:05 -0800 (PST) Date: Thu, 19 Dec 2024 08:27:05 +0100 From: Michal Hocko To: Alexei Starovoitov Cc: bpf , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Andrew Morton , Peter Zijlstra , Vlastimil Babka , Sebastian Sewior , Steven Rostedt , Hou Tao , Johannes Weiner , Shakeel Butt , Matthew Wilcox , Thomas Gleixner , Jann Horn , Tejun Heo , linux-mm , Kernel Team Subject: Re: [PATCH bpf-next v3 4/6] memcg: Use trylock to access memcg stock_lock. Message-ID: References: <20241218030720.1602449-1-alexei.starovoitov@gmail.com> <20241218030720.1602449-5-alexei.starovoitov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 503A2C0002 X-Stat-Signature: qxjfwqy3f3xhngafq3gef9cor1bqs8ik X-Rspam-User: X-HE-Tag: 1734593213-904850 X-HE-Meta: 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 0Og0YMMP +nZIrqcHEr2ophDepfHmXSuV3Onp/PZBav18W/y0ywEGX04EFd9zKec1rnDjaxvaOAErSxMN0JuqTcIHNKRuOYBR1D1geFprZboDXB9hrKZMKN1NyrZSziZ63GNjQp1U/rMgBK/CN6T+lxBqZDa0xnMetzwzwgqpLa1LXuQ95bRIdAjLT09bt+7Vu3IibA5uT/FrtvUMxutVmzYB/HQ07n0Hcde17G++fvbS358nkiCs6V5twEJkr/VTinUGCyPWa0U1qQJaP/rGVZw8PW5qrBFyW0R1tv3m360QAxvzTcylYfxp8Aoizg2SXjVBE4THpVAXKQvHfAqj59LT3xaarLUSLYM/lDEadiCAQPndZ1xpL6ofe+CPGD/j+804t1aptcPYykmLcimebEOHwcJYSJpJasrytzXnYPSFsEEXx+di6UuY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.091416, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu 19-12-24 08:08:44, Michal Hocko wrote: > All that being said, the message I wanted to get through is that atomic > (NOWAIT) charges could be trully reentrant if the stock local lock uses > trylock. We do not need a dedicated gfp flag for that now. And I want to add. Not only we can achieve that, I also think this is desirable because for !RT this will be no functional change and for RT it makes more sense to simply do deterministic (albeit more costly page_counter update) than spin over a lock to use the batch (or learn the batch cannot be used). -- Michal Hocko SUSE Labs