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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id i13-20020a5d438d000000b002cff06039d7sm901837wrq.39.2023.04.13.02.46.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Apr 2023 02:46:47 -0700 (PDT) Message-ID: <2b8024d7-3526-6710-5ddb-9c0852bc299d@redhat.com> Date: Thu, 13 Apr 2023 11:46:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH v6 1/3] mm: add new api to enable ksm per process To: Stefan Roesch Cc: kernel-team@fb.com, linux-mm@kvack.org, riel@surriel.com, mhocko@suse.com, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, hannes@cmpxchg.org, willy@infradead.org, Bagas Sanjaya References: <20230412031648.2206875-1-shr@devkernel.io> <20230412031648.2206875-2-shr@devkernel.io> <30b948fe-7983-39dd-9565-9f92ffd9101b@redhat.com> <33f18dde-8ff8-5ec6-9bee-3c1900c2bd83@redhat.com> From: David Hildenbrand 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-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9688C180016 X-Stat-Signature: umc3gz6ud8icrjjpnt6hjspqrooa9ymu X-Rspam-User: X-HE-Tag: 1681379211-574594 X-HE-Meta: U2FsdGVkX1/n/HwCJevXg2I10Xt5JvMhDKPHnYoEV5pi0wsHeKbMerQWt3PVwdWAgtrQ5srQfYr5LOQtO4SRCH4Dg1Pj58QkB59PC2dQ7dU16SN9ovmEnLyPbyxQUYZnZFgiHtfbeYwf0mW0CbozThybLm/Qdvi5lV2dyltFPFwuOL5E7rg3m7IU/Z8vKcmHdlpYLHQsdr0R3lLBEHlcAnYp6J6KHqvHa1XPcovaQ9Is1RIeTJIjRVOTrJsG5bKlhj3PLkMRbP+a+GfEVZ3jhfCEfipbRXD/ajhXBk3MJmc6RmKk8toSyGosfMbNMaY3MFy2ruVWyhUvN1fwjDzV6nRahFqwVAJ/RDdGpGVhe7/wvHan1oFN7iqWYZ+qVgA3PwKn01FvNrfbgx0xNiacgOR0QH2k78zSh7M15jiPKEUTS+CmxDHkfTTqqCwJ9eQmEop26UYKh/Ao7QqYPRaMYqNtxTEgcRxpiBSHEyKvc4h7/62+AexwhoDTaEJT+nIotN4bg6fiaFg2994O+AyDosMRBqGUbtRrAbwQ2wU6Q3bmFWBr2pd+KoTW8MbyS3KHUSFPNGFzN4OP0EhI7XKCZy++rW3zThnrwPjL+i4480ZWhYGtrZN9o3DRpFdvdli01cINt9UfLECm1ml8l2hvfTKxNY8/Zy4dqChFyqCipMqd72pG38I0QF2oYkC6IHoQLOd5p0wIetKH9DvTB/Swerh3T2AoSLxsH7grjgzVSabUZRuaWbAZ/1ZYO6Mxc56StcMlv5QSYmrJLVSpaxpHR2XYbj+0UYG3IznhA/mSbiOblZgX4nvP9/Q+k656qWMprDec2HB8NoizcIMnMb5TcI5LMpcpEGx/1hADhOZC4uRXbFjHFJPicfRDqiQrsM6Dhi/EEKMyDzC16I2/l7ZlWpbwO8NTj1axXhLsozS0XaHirLd/u11WZr0yJ8qOMmHXk+wQlwlmAmKBui0sbdV QagJ8ubU MHRu7pZ1BNgKAiZFq12l7sTD6aNKYzxkD24/yXVbONb93jZIwK2GS3uRvMnQwHJnoTjewShTVVAZRZrWRisSc6c38OWaTqeiqOWeoIYyQhwkwEBzFnw84p3RbOtX1mb03HzoLFg1bTfJwhbm+YQhkP+/brsnYuk65hHjIH7WUepGZzwSJIg2DqDb/YxV7mXRPkehXr7qxul1wX0XDnE58HZQm0bEEGdYVK8Jof6V4Elxk6is72DluuCRx+bwUEQo2PJhA6slZRXLgzCVs2BIlzsLPFb+ZUZeba5bNtHToyS8iQWtVvWgVnUw/Xqp+LgGgrk9b0gasLcnpmtdfk9Stgp6bxzIvt4RmDnPdxXhmuCh8hcp9jU2kKYntoGT/f/qVSzBS+CfIZWeRBzvGt2thtmAq79uYxLCrygrNeZ2Pfw1sr/XYCjzCK9F1bSsJqvDZyW0g 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 12.04.23 21:55, Stefan Roesch wrote: > > David Hildenbrand writes: > >> On 12.04.23 20:41, David Hildenbrand wrote: >>> [...] >>>> That will work. >>>>> work? IOW, not exporting ksm_add_mm() and not passing a flag to __ksm_enter() -- >>>>> it would simply set MMF_VM_MERGEABLE ? >>>>> >>>> >>>> ksm_add_mm() is also used in prctl (kernel/sys.c). Do you want to make a >>>> similar change there? >>> Yes. >>> >>>>>> + * >>>>>> + * @vma: Pointer to vma >>>>>> + */ >>>>>> +void ksm_add_vma(struct vm_area_struct *vma) >>>>>> +{ >>>>>> + struct mm_struct *mm = vma->vm_mm; >>>>>> + >>>>>> + if (test_bit(MMF_VM_MERGE_ANY, &mm->flags)) >>>>>> + __ksm_add_vma(vma); >>>>>> +} >>>>>> + >>>>>> +/** >>>>>> + * ksm_add_vmas - Mark all vma's of a process as mergeable >>>>>> + * >>>>>> + * @mm: Pointer to mm >>>>>> + */ >>>>>> +void ksm_add_vmas(struct mm_struct *mm) >>>>> >>>>> I'd suggest calling this >>>>> >>>> I guess you forgot your name suggestion? >>> Yeah, I reconsidered because the first idea I had was not particularly >>> good. Maybe >>> ksm_enable_for_all_vmas() >>> But not so sure. If you think the "add" terminology is a good fit, keep >>> it like that. >>> Thanks for bearing with me :) >>> >> >> I briefly played with your patch to see how much it can be simplified. >> Always enabling ksm (setting MMF_VM_MERGEABLE) before setting >> MMF_VM_MERGE_ANY might simplify things. ksm_enable_merge_any() [or however it should >> be called] and ksm_fork() contain the interesting bits. >> >> >> Feel free to incorporate what you consider valuable (uncompiled, >> untested). >> > I added most of it. The only change is that I kept ksm_add_vmas as a > static function, otherwise I need to define the VMA_ITERATOR at the top > of the function. Makes sense. I'll review patch #3 later, so we can hopefully get this into the 6.4 merge window after letting it rest at least some days in -next. -- Thanks, David / dhildenb