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[81.154.179.160]) by smtp.gmail.com with ESMTPSA id l20-20020a7bc454000000b003f42e008c8dsm12664696wmi.44.2023.05.22.13.34.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 May 2023 13:34:32 -0700 (PDT) Date: Mon, 22 May 2023 21:34:31 +0100 From: Lorenzo Stoakes To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Rapoport , "Liam R . Howlett" , Vlastimil Babka Subject: Re: [PATCH] mm/mmap: refactor mlock_future_check() Message-ID: References: <20230522082412.56685-1-lstoakes@gmail.com> <20230522132851.ccc9fafac91d7eb9ba922e94@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230522132851.ccc9fafac91d7eb9ba922e94@linux-foundation.org> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2E2A510000B X-Stat-Signature: 5zbk1khaq4nze4eapk9gu7q66da88j9a X-HE-Tag: 1684787674-368469 X-HE-Meta: U2FsdGVkX1+8W4MZS66vCBxEjm+G0vlUAKOIy1CEqE+Z2vQa970WzaEPhs9iZ7dr2Ge6xZFuLyrs8mcnc6N4mIr827t1CJ9X6vhP+9TvfxdmP4qU3/byxxJU0aPMxw/v+EEay+quB1Mq5U9ep6GPE2dQlfRfFBezJgFvfpMDra2+m1wuk2FOz6QOKhd/2a68IDbnmw8qaKoQG4wOe1/VKBBDf5Oaa52cIIVHdrjSnc35lYoPN+wToCP62SA7oZkrIFrIvZwN+wtDfSRUejHYwna9f1pfo1p7sMEVwI6L2YZlp/VgjxII3YrD4WLAGuzuuNiTPG2WiJIAWZcPaXkV96GN6PRRx7t1U630lB+d7BnpDkamviKE4wdOBGQWmQuAXPRSQnMEuT8uTWjHtzj++nOzZ2F1vIQpULUYWZwwWyfHQ0eIxjg9YUJu/WZqC2l9mfxCCYDk5j/9CNIUax0Xc9WFPdK4+cg67UnWqEYPSY2Opdet+nqQ2a2pbKLnCGsCh4xkjanJPGMuwwCs+K/5lz7J/LlVjZUQ0lUsEST0eQHOcqyb45aClnEmwPQ3vhYczLsZiibSzXaAd2ZLLqf7lqoc3Oji7bPF0X8voYnrxe5wZm4Fa9Qs74a6K35/PqqvRvBcAFCLTTOiUTaUO4mAw+taJqm6eZY0GQ5obhk01WetxEAqUCjErzBuwWExjbVYZukr4M8TjPBysnLMky0+XNdqdnXnpeVucNShQOdOKHciGwlEi62fkfQkW3yF1h4EHJRNQHegVIhzrlTqqeCBJvnagE0zr0OBQJ1xDXhi7QDfXE6+w3en8ZHSwYFsFlnhXaS2mjWERqq7GSPf427z+c2Hflr+YQ2zElJ0P0RxU0E2zbUg37Xf3vUxzL1Z5V/YEaCU9e/SigE8JWdP5y+jNU9k6t1Kw6zdkBT8l5Ifmsec3lofVbNhb37QZKYDyoF1TiikVKuRLD8tH/2LEhz 4zjWsVdM SNWtyecD9AYMDGcpRrVu+CM0CemKjtH4FzMnUzJL6bNLb4C0YXW7KWWqzYul5rnG9FBt0JJGOAmsd7JZq1HiUuloPTdcfBVDIU7Aq8ayg/aNb7MUnlTTQ1CBVuBdvWgqjZVakPfPZ+PBfiwVsK0db+f1yCrLVosOP4yXnaq5QuxyaP8c71a+IyQbUIpJ2DtGbqh+e2jgVwhsHGrAxHqe3OFHDwsgGdifY6Bb/L4vM1GQA/VfLSvxemp85lsfmY+B2HuzU+cZudoZk03IBKF79tgvrbFVtUI8Q3E959vJE7vU1ZuQgHcNjKkzVLIGQtdbitywbWBCS/Qg6flBjzW/JMDR2griCankbqLMtaXfhmThjH/JTEKnk8lcwcM9c32q13fN1yEERpvPZeM3xHZEjkfl53Nt+yL0+yo02kbSmMmNiqOEBEcEiLlsWZgyRXTJygXEmpIDDQnJNsRM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000308, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 22, 2023 at 01:28:51PM -0700, Andrew Morton wrote: > On Mon, 22 May 2023 09:24:12 +0100 Lorenzo Stoakes wrote: > > > In all but one instance, mlock_future_check() is treated as a boolean > > function despite returning an error code. In one instance, this error code > > is ignored and replaced with -ENOMEM. > > > > This is confusing, and the inversion of true -> failure, false -> success > > is not warranted. Convert the function to a bool, lightly refactor and > > return true if the check passes, false if not. > > Yup. > > I don't think the name does a good job of conveying the > function's use. > > > - if (mlock_future_check(mm, vm_flags, len)) > > + if (!mlock_future_check(mm, vm_flags, len)) > > return -EAGAIN; > > if (!may_mlock_future(...)) > > or > > if (!mlock_future_ok(...)) > > ? > > Yeah I struggled with this, because the check only triggers if VM_LOCKED. I was originally toying with can_mlock_future() but of course, it also returns true if !VM_LOCKED... I think your suggestion of mlock_future_ok() works well, could you change it to that? Thanks!