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[109.81.90.71]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4922fa891acsm164250535e9.9.2026.06.17.06.16.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 06:16:51 -0700 (PDT) Date: Wed, 17 Jun 2026 15:16:50 +0200 From: Michal Hocko To: Kaitao Cheng Cc: Dennis Zhou , Andrew Morton , Uladzislau Rezki , Tejun Heo , Christoph Lameter , Vlastimil Babka , muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kaitao Cheng Subject: Re: [PATCH v3 3/3] mm/percpu: Avoid IO/FS reclaim in backing allocations Message-ID: References: <20260612022648.13008-1-kaitao.cheng@linux.dev> <20260612022648.13008-4-kaitao.cheng@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed 17-06-26 16:56:56, Kaitao Cheng wrote: [...] > __GFP_NOFAIL is actually unnecessary here. The main reason is that, > for now, I have not found any in-kernel callers that pass __GFP_NOFAIL > to pcpu_alloc_noprof() or its wrapper functions. The reason I added > __GFP_NOFAIL was to address the issue reported by sashiko, and I > provided a detailed clarification in the link below. > > https://lore.kernel.org/all/3de3a89b-92f0-4cd2-9f41-8e853eae4e78@linux.dev/ > > We should probably revert the current patch back to the v2 version, > and then add some comments explaining why pcpu_alloc_noprof() must > not be passed the __GFP_NOFAIL flag, as suggested by Andrew Morton. Do not add support for nofail semantic until there is a clear demand for it. Supporting this semantic is a big commitment and it shouldn't be done without a very good usecase in mind. -- Michal Hocko SUSE Labs