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[46.135.3.11]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442cd35fb49sm7245725e9.28.2025.05.07.10.03.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 May 2025 10:03:37 -0700 (PDT) Date: Wed, 7 May 2025 19:03:30 +0200 From: Mateusz Guzik To: Linus Walleij Cc: Andrew Morton , linux-mm@kvack.org, Pasha Tatashin Subject: Re: [PATCH v2 0/5] fork: Page operation cleanups in the fork code Message-ID: References: <20250507-fork-fixes-v2-0-82ab1e42cde3@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250507-fork-fixes-v2-0-82ab1e42cde3@linaro.org> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1F19A160016 X-Stat-Signature: 785jmgfxajc9941a5bws9ars33swyrso X-Rspam-User: X-HE-Tag: 1746637419-720018 X-HE-Meta: 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 a8oXTqI6 b+KgzjjUzIw14XVttaoJtC6X3RoeTtUkA7ic8NidnFTLAvNWxrKqHnITY4RIzvkuEVFP0me2kzydSX9ZJsCwO2rG0Zw0MQxpTTMQyB7/CmgPfeEAlkIeBPKCr8V593lxkPzjM1JzNSkPFY8wM0vEAu83jQJE3hXYN4TSIL8Qqyfu2Me/qJPrRGBV76kXypOmaeMtUQBf/CLr8soELU4WY+8srbQ5v0naBXF60U5njmbClaNJy5Uefv/9eSMZaL3KCUROQJx4BDUn0LWzINXoHkKXeShQdxLnLTVdh1KSQkZcWYqbicDJuCvGfye6aBYI+KnALRhwycsqky7/2XOJ+Jn8mRHco/L7fbiRA6E66zPrbcYSsaxQLeS4y114JrP+rHK2hl5bEJam3aKU0PiSq0lrzFBWqIxTaeuIqcU/HpGffnH0CBdj10LVsMIS4VQrUAFAH9oWkrbcCi7GyCKs8ileTLCApx29KQyX0 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: List-Subscribe: List-Unsubscribe: On Wed, May 07, 2025 at 02:46:26PM +0200, Linus Walleij wrote: > This patch set consists of outtakes from a 1 year+ old > patch set from Pasha, which all stand on their own. > See: > https://lore.kernel.org/all/20240311164638.2015063-1-pasha.tatashin@soleen.com/ > > What the code mainly does is make the fork.c file more > oriented around pages and remove reliance on THREAD_SIZE. > > These are good cleanups for readability and in one case > (last patch using clear_page()) a performance improvement, > so I split these off, rebased on v6.15-rc1, addressed review > comments and send them separately. > > All mentions of dynamic stack are removed from the patch > set as we have no idea whether that will go anywhere. > > This is mostly MM related so when the patches are ready > I expect they would land in Andrew's patch stack. > The ifdef clean up looks fine. If readability is concerned I think a big problem is code duplication in alloc_thread_stack_node(). The code instead obtain the stack space and only then do the memcg charge and tsk var popoulation work. The real problem here is that the cache is incredibly primitive and in fact with a performance bug (ignoring NUMA affinity -- pages get added to the cache and removed from it without any regard for that aspect or the node parameter!)