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[209.85.218.53]) by smtp.gmail.com with ESMTPSA id o18-20020a509b12000000b00497d8613532sm7262918edi.5.2023.02.13.14.19.36 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Feb 2023 14:19:37 -0800 (PST) Received: by mail-ej1-f53.google.com with SMTP id sa10so35433516ejc.9 for ; Mon, 13 Feb 2023 14:19:36 -0800 (PST) X-Received: by 2002:a17:907:984a:b0:88f:a9ec:dfd7 with SMTP id jj10-20020a170907984a00b0088fa9ecdfd7mr268381ejc.0.1676326776594; Mon, 13 Feb 2023 14:19:36 -0800 (PST) MIME-Version: 1.0 References: <20230213140812.db63c7146ebc396691594b73@linux-foundation.org> In-Reply-To: <20230213140812.db63c7146ebc396691594b73@linux-foundation.org> From: Linus Torvalds Date: Mon, 13 Feb 2023 14:19:19 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] hotfixes for 6.2 To: Andrew Morton Cc: linux-mm@kvack.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8A8724000B X-Stat-Signature: hsk8b6f6raffpr1817g3rxou1qx4rgmx X-HE-Tag: 1676326779-159128 X-HE-Meta: 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 mliAd1dc 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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, Feb 13, 2023 at 2:08 PM Andrew Morton wrote: > > Kuan-Ying Lee (1): > mm/gup: add folio to list when folio_isolate_lru() succeed Ugh. I really hate fixes like this. The problem came from mis-understanding the return value of folio_isolate_lru(), and thinking that it was a boolean success/failure thing. It wasn't, it was an integer "success/errno" thing, and the sense of the test was wrong. So the patch is - if (!folio_isolate_lru(folio)) + if (folio_isolate_lru(folio)) continue; but at no point was the code *clarified*. Wouldn't it have been much better to write the new code to be if (folio_isolate_lru(folio) < 0) continue; to actually make it clear that this is a "negative error return check". I've pulled this, but I really think that when somebody notices that we had a silly bug because of a misunderstanding like this, it's not just that the bug should be fixed, the code should also be *clarified* at the same time. Linus