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[2003:cb:c717:6a00:e38f:c852:dc11:9146]) by smtp.gmail.com with ESMTPSA id g10-20020a7bc4ca000000b003f171234a08sm5302275wmk.20.2023.04.21.10.21.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Apr 2023 10:21:38 -0700 (PDT) Message-ID: Date: Fri, 21 Apr 2023 19:21:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v1 1/3] mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0 From: David Hildenbrand To: Stefan Roesch Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Rik van Riel , Johannes Weiner , Michal Hocko , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Shuah Khan References: <20230418051342.1919757-1-shr@devkernel.io> <20230418152849.505124-1-david@redhat.com> <20230418152849.505124-2-david@redhat.com> Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C0FAA40019 X-Stat-Signature: zwb6epa5fp1xh3fuw5f49p8jhm1rpbpe X-HE-Tag: 1682097712-120533 X-HE-Meta: U2FsdGVkX18N7JpmOAabqoKvdM3K4t+EKjwbvbjIOotKOf31SRlejZsTBijuuB6v/zWl2/fl620XDPkijSu1HTFsBmB1EtPbENEKV7mUUPg7PXHaI3coPMwUlMyTgeHqYjApQ/YA0MymNq+wFoPf2LCU3zh+V/2kgmVCVscPR66nccxmybpqshgrDI+4y8N9h5Q2ESjCdHY/DSQAzLj+Twj1G4KNpPbEbD6kkU7c8TNFmgeXZnLDA94ZARFmEOwApTT+Lk7hp8nnIy1WNoWWbPzZ9kZyp6vUaSdYB5vIdnbYIoz0D6cNHMyCzJrDtII0DPxYoxGgdRaGLFGgmxo3uHNJYAVXt76KrRd73gI4GhRC9d8bwhn+RWnnP7nbSSGz+Sznrk2TRgttGItZT45/xeAiwncKfAL7lqILWWU5/WfUpBn5+fXk4EtuAs/laNvMQZ/CUUQqLxUexYeupjr2MRO8Wgxcw7mZGF7svaI2NFbvfIAI5Ml1+sNh9WcugPooCh0qZD6qIGb5gdauI/3MFtDzaZOC2Z/pb9iiJ4MNrEF4mQtDyxE3Wu1DtGOWGxg20KtzOUb+9Z+hBVFEuP1S5f1EyCj9fUddImo9hEgFXS9yvB0AseFQrWK6tmHWcLNXV2lqzr4sunPHoRlJG/I+h5UExxUdVHLQRwqKol9DKqaiEh72EMEzCUDvolnsMIkANhVswuMhu96xte92VPhSCXFBWrL95QjSV0T3/Vjh57aVM1v3oe2VtODvoU4EdFzD8DeeKtLScmlcHgQAQ/QCqQKjSx9WEeo6ms1X6fSSpczUqYjaQ1lh0YpDhgbim6CIbJ1n3K3+j8BB82vWExPW54nSJ536gcGTbDu24FgMd65+IzTKny1KXiZSVuOh3Sw9Zpgh3Hz0g49P9vjBsMqJ42ea8gWflkG2C1NMmu2XwA9yrB5aUV9AOtZgxFfoJmNGrQbthWT8R9PMM6l7JAv KFaGTH5N RBuy8hw+WDkzCPewS0O7952Y3Ot9hpDFdwvFyvXux6iCKWR3MTDWzCKdQAEct1CegT5Mv9Anm0tteyQqvBqxRO6Rm/VjcjLtIk73bNS5Guj7bI/vcFja2uCyG5hUq3SymaiN+A7yxaMKOXHTmLI5PZEBSssd4x0//lgRjTFInFSkqbamwxz9LFSGis1J0U5ZBV2mhQfb9TRGqigsInmeXTjYTx0oWFPWOAW/yt9LQBkxdmH6auzAv0j01/7claktLHT3qh61LE2Df1IjQ5GvBuXp0hdbciuIihHtTE4XLlh/5o9nrvfEmlDfVavw+ATlq06fYSmkJy60B8JEkKy599of7/IDAI2DhPbaZVqTPbO9nGwjWNTcPlb6Doq8ZffpfPIEuS1oQ71W8WQ7t+bkWCthE0kWobUsMtiZQvUMyh8vMxxo= 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: >> I understand we want to keep the name "symmetric" with >> ksm_enable_merge_any, but it also unmerges the ksm pages. Do we want to >> reflect that in the function name? > > ksm_disable_merge_any_umerge() is suboptimal. > > As ksm_disable_merge_any() now reverts what ksm_enable_merge_any() ended > up doing, I think it's just fine. > > (it would be a different story if we'd be using "set" / "clear" > terminology instead of "enable" / "disable"). > > We can describe that in the comment. > >> >> Can we add a comment for the function? > > Can do for symmetry with ksm_enable_merge_any(). > +/** + * ksm_disable_merge_any - Disable merging on all compatible VMA's of the mm, + * previously enabled via ksm_enable_merge_any(). + * + * Disabling merging implies unmerging any merged pages, like setting + * MADV_UNMERGEABLE would. If unmerging fails, the whole operation fails and + * merging on all compatible VMA's remains enabled. + * + * @mm: Pointer to mm + * + * Returns 0 on success, otherwise error code + */ -- Thanks, David / dhildenb