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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH v2 0/4] Change the return value for page isolation functions To: David Hildenbrand , akpm@linux-foundation.org Cc: torvalds@linux-foundation.org, sj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, naoya.horiguchi@nec.com, linmiaohe@huawei.com, osalvador@suse.de, mike.kravetz@oracle.com, willy@infradead.org, damon@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <5064ee08-792f-14f2-6f2d-26e81af8a239@redhat.com> From: Baolin Wang In-Reply-To: <5064ee08-792f-14f2-6f2d-26e81af8a239@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 15re87cw39y87g3xtft51m1ymo99gm35 X-Rspam-User: X-Rspamd-Queue-Id: CBBBB8000D X-Rspamd-Server: rspam06 X-HE-Tag: 1676424100-521698 X-HE-Meta: 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 HNyzgE+F NTf0ZAlfSiegVcG6AIrvGcyA9uVbqbv+D6gAL+Rb8xcCTcGGriH9blqvL/b7LKl2iSPMwokx40TCqkCEdjlRWxuRb37sYWafM9CFairWHn8iJgDT/J4OBu/hgS7Hu6JMgXV93 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 2/15/2023 1:52 AM, David Hildenbrand wrote: > On 14.02.23 14:59, Baolin Wang wrote: >> Now the page isolation functions did not return a boolean to indicate >> success or not, instead it will return a negative error when failed >> to isolate a page. So below code used in most places seem a boolean >> success/failure thing, which can confuse people whether the isolation >> is successful. >> >> if (folio_isolate_lru(folio)) >>          continue; >> >> Moreover the page isolation functions only return 0 or -EBUSY, and >> most users did not care about the negative error except for few users, >> thus we can convert all page isolation functions to return a boolean >> value, which can remove the confusion to make code more clear. >> >> No functional changes intended in this patch series. >> >> Changes from v1: >>   - Convert all isolation functions to return bool. > > Acked-by: David Hildenbrand Thanks. > > Although it's controversial if > > if (!ret) >     ret = -EBUSY; > else >     ret = 0; > > is really appealing to the readers eye :) > > ret = ret ? 0 : -EBUSY; > > It's still confusing. > > would be better as > > ret = isolated ? 0 : -EBUSY; > > IOW, not reusing the "int ret" variable. Yes, pretty clear. Will do in next version.