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[109.81.88.1]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5d80701c94csm2460513a12.85.2024.12.20.23.20.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Dec 2024 23:20:06 -0800 (PST) Date: Sat, 21 Dec 2024 08:20:05 +0100 From: Michal Hocko To: Shakeel Butt Cc: Alexei Starovoitov , bpf , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Andrew Morton , Peter Zijlstra , Vlastimil Babka , Sebastian Sewior , Steven Rostedt , Hou Tao , Johannes Weiner , 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: <20241218030720.1602449-5-alexei.starovoitov@gmail.com> <7s6fbpwsynadnzybhdqg3jwhls4pq2sptyxuyghxpaufhissj5@iadb6ibzscjj> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7s6fbpwsynadnzybhdqg3jwhls4pq2sptyxuyghxpaufhissj5@iadb6ibzscjj> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3E0FC40005 X-Stat-Signature: axjazkug6dhz9unr8jzdfefu7uk66zts X-Rspam-User: X-HE-Tag: 1734765581-478856 X-HE-Meta: U2FsdGVkX1/5rCaipKScj8SMC7ww67v7A9hKSKtYiWEWF6yBb8Rt4DBGReS6IyV6PZ9Bn9qOlcM6AER35KqsB7fGkkHjsmSIigO4IxfILV0KhApSmCMmiFEahnMASq1uQSj0Ep1/p1MjV6yMj7rOWXn92J/3w0USYt0Xfh5AKnOc0O7Z5xxF42Bao1CkxF+P95rkZ0ZDlcWoDTE4dN1h00wPKIwzkWRqQkRiAdnK95dXhEK8EhKLMSu98dl/o0lOAIgta41hBEorup+M7LUAsxSVNOQbvm9pWopHkdCF4TDjTTOjKDZPz6rJn57ZjNMDXJhq6IxQlYmdniNQnVZ1ubZ6gj2FZbKDpNlCu1iXc+TGya9UYu+HsIKj3o6/lxtaZINyVzqisQXtlBe6UpDZl0sTn7SY7geUEdx9PJQ7aS89DNKCIHLr31yISkgZXg0qvoKtYsSemcz/4GgCaN3DU3VvZ2G8UsLQdrNHoHoi6nSP3WDDFTA+FYfOxNUqwdc8pSHTt+g9/ZXZTYO/8rsQQJBsxYPuhXXGZzdXQ/5/bsm2Ku3APauweJHL34VJrn9Ujkj3APvF/pHo7eGQWCisEicwENYCQg9uGMospTBMbN1DI2+KPH3ye2JluJ104yYPlMmePBL2rarVgGLVroFTOItNZFD900wX0DPTIjCUPGTyCHFMZWFg3UKYZq3opsSIIy+xnWwN2SJkvhJSb4jp54PQ9nurEoSru+fMHf57KEvMVgwri9lAD995LrloF8FXYfAeATuhiD+/py7dHPMB120tQkvry9gn1k8bwL7pR8PwiIu1c+EGJhbxnX0/ojNicZHtqnrcnR8RwGSxNLzw0qIwE3OqZisH1eQYmQW0m/6GcxeGFwZQRK2OsX+haLLbIEkhgTNPYNFn32h6csduzHjDp0kHmOfpZNkDBxG1X8gyF5k1ECPYLSX4TgHdj5mg30BZzW69EPk33BB3UjM PpW7j3fl oIcCh1uffgUmakv3kEcjApqhr3UdXnqJvSOW95J8iqD/fhNR/0zkqV12yVA5itiOckhBxw9ATP3YKUkjkZrkNDYY4Sgao4F5fi8FdhiOXCo5lOSpUrzSet2MB6odrCFqPW3xp59oBY9qlIGFCHckOqZYoOckZzkRnBIzZFVr6SxfmFM3R8QzuJLOKaS7g6yMVfEqQHE2UGtBj7t0jD5wGwKPZk03VGJiTekT6wWO4HeM4tuEL5DJ4a+8STlLw8uXeUBEe6KWcCuxYc5fd3B1yG3O1XcILdyXCZdwZQgxbf201rU2ArKjR65/4PKqjFfbI7h2ehifAkciY/4tM+8l7OTs6scPe6PvBRYjXvlKWJzDGcnB5QWXWp9VwV6pYr8B7LGVC7MtZ3QezvnQaHMKyBNApQU5d2cyRCsOo/FtXIPT3NZ6aMq9q07bAgl5eaGf2wPNmVHb2Un5u4bEdT/wVqdMg5imtGY9/6gN/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000503, 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 Fri 20-12-24 11:45:47, Shakeel Butt wrote: [...] > I think the code is fine as the overcharge amount will be refilled into > the stock (old one will be flushed). > > if (gfpflags_allow_spinning(gfp_mask)) > batch = nr_pages; > > The above code will just avoid the refill and flushing the older stock. > Maybe Michal's suggestion is due to that reason. Exactly. This surely begs for a comment to explain that. > BTW after the done_restock tag in try_charge_memcg(), we will another > gfpflags_allow_spinning() check to avoid schedule_work() and > mem_cgroup_handle_over_high(). Maybe simply return early for > gfpflags_allow_spinning() without checking high marks. Right you are. Btw. I will be mostly offline until Jan 6. -- Michal Hocko SUSE Labs