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AJvYcCVkjm11K1zQDJN3XLkSWzmI6FatUltd7o2o0xntCl8+KJMHghZDjjb6hHrtKXNSM517KdS8v5UeGA==@kvack.org X-Gm-Message-State: AOJu0YxuLSHzv2CIkzZALmslaf9073YLyiG5zFQSFBKNZUuLBKN0LacC rFtTQU4CZx15Sjw9fEoOwXzQNKEHZQRAb9JPoymq2ww/CmfdJcP2lIDOpqP6o31KbWItCDTGMWT kmM8AkUYS5y6IbvUNY57hFjBIEvM= X-Gm-Gg: ASbGncs2jT8AbffMym9Gux6ig2bu0yuRDqHH0sfwjFCxRSjGXMY7raakSl7T2NGRKmI KRndeY5w+ASnfknvF0YUMILlj4sDxs8c= X-Google-Smtp-Source: AGHT+IG+ev6TKH4lNjEgnAhU9TSWMD2LVnvtGUP3ZtT+Ly9uZqCGStRNJBECTwGkDWJxV+X0tUztL6bslr92iBQmWUo= X-Received: by 2002:a05:6512:2203:b0:53d:e592:5415 with SMTP id 2adb3069b0e04-53de5926f10mr4124765e87.34.1732597456490; Mon, 25 Nov 2024 21:04:16 -0800 (PST) MIME-Version: 1.0 References: <20241125210149.2976098-1-willy@infradead.org> In-Reply-To: <20241125210149.2976098-1-willy@infradead.org> From: Hyeonggon Yoo <42.hyeyoo@gmail.com> Date: Tue, 26 Nov 2024 14:04:04 +0900 Message-ID: Subject: Re: [PATCH v3 00/15] Allocate and free frozen pages To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , linux-mm@kvack.org, David Hildenbrand , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: A57D5180008 X-Rspamd-Server: rspam01 X-Stat-Signature: krzcrmhaxg1hdt75yophuj7ydnjb17bm X-HE-Tag: 1732597454-511678 X-HE-Meta: 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 zSWydfb5 udrXy1XyrcGcoI1iYInmSLcsOCdWhzLzYIeCxukz+nXiAhA0gzeam1AYaQaWD96b36nkx8MgBMTwRlBqUT+1mEXcTmvA5F5QZysgst4orASG/QUvbIOOmFDq/vOlm5FBeJrq24fqKHazSSPb//eaikZEuOP4BAQnOFuLHPve+EeKzk6lgRDjpqEir+gAwSD+9dJjaqnJqEXZj7G3yE+fITygNru5DChSRJttZ5YEu87OVTiXYwKI0AjxqF0PpU5gnXag3rU+Hql591R9Efba3rAEjqyv5iSY1S5EISzv8qWDrFwvgsnHRWJhRcQs1pLPLWQq/AWr4M0UYEKxTk/tbqUbbkcygwzjAzIA23b+j+IPJfdPhZUW4gpOZlaiUF+xfjxPGk5Z3LiqBkKT9mXoHg/5SWPpezQuLQ/wzAJKml1rdPPbkamXEzscnoQgyfJE6hDuVSDKMPupKnTc= 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: List-Subscribe: List-Unsubscribe: On Tue, Nov 26, 2024 at 7:38=E2=80=AFAM Matthew Wilcox (Oracle) wrote: > > Slab does not need to use the page refcount at all, and it can avoid > an atomic operation on page free. Hugetlb wants to delay setting the > refcount until it has assembled a complete gigantic page. We already > have the ability to freeze a page (safely reduce its reference count to > 0), so this patchset adds APIs to allocate and free pages which are in > a frozen state. [+Cc Vlastimil] I think with this patchset, we can finally remove the memory barriers used in isolate_movable_page(), alloc_slab_page(), and __free_slab(), because folio_get_nontail_page() should fail for frozen pages? for reference, the patch that introduced the memory barrier: https://lore.kernel.org/linux-mm/Y20BRJmRzRVMzoJw@hyeyoo Best, Hyeonggon