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Shutemov" , Vlastimil Babka , William Kucharski , David Howells Subject: [PATCH v14 007/138] mm: Add folio_put() Date: Thu, 15 Jul 2021 04:34:53 +0100 Message-Id: <20210715033704.692967-8-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210715033704.692967-1-willy@infradead.org> References: <20210715033704.692967-1-willy@infradead.org> MIME-Version: 1.0 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=mDPsWFMU; spf=none (imf13.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Stat-Signature: 9c1nry61y9h6jq5k5qcju6wzwkophuuh X-Rspamd-Queue-Id: 9A27310072E1 X-Rspamd-Server: rspam01 X-HE-Tag: 1626320573-241714 Content-Transfer-Encoding: quoted-printable 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: If we know we have a folio, we can call folio_put() instead of put_page() and save the overhead of calling compound_head(). Also skips the devmap checks. This commit looks like it should be a no-op, but actually saves 684 bytes of text with the distro-derived config that I'm testing. Some functions grow a little while others shrink. I presume the compiler is making different inlining decisions. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Zi Yan Reviewed-by: Christoph Hellwig Acked-by: Jeff Layton Acked-by: Kirill A. Shutemov Acked-by: Vlastimil Babka Reviewed-by: William Kucharski Reviewed-by: David Howells --- include/linux/mm.h | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 0e14ac29a3e9..9eca5da04dec 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -749,6 +749,11 @@ static inline int put_page_testzero(struct page *pag= e) return page_ref_dec_and_test(page); } =20 +static inline int folio_put_testzero(struct folio *folio) +{ + return put_page_testzero(&folio->page); +} + /* * Try to grab a ref unless the page has a refcount of zero, return fals= e if * that is the case. @@ -1246,9 +1251,28 @@ static inline __must_check bool try_get_page(struc= t page *page) return true; } =20 +/** + * folio_put - Decrement the reference count on a folio. + * @folio: The folio. + * + * If the folio's reference count reaches zero, the memory will be + * released back to the page allocator and may be used by another + * allocation immediately. Do not access the memory or the struct folio + * after calling folio_put() unless you can be sure that it wasn't the + * last reference. + * + * Context: May be called in process or interrupt context, but not in NM= I + * context. May be called while holding a spinlock. + */ +static inline void folio_put(struct folio *folio) +{ + if (folio_put_testzero(folio)) + __put_page(&folio->page); +} + static inline void put_page(struct page *page) { - page =3D compound_head(page); + struct folio *folio =3D page_folio(page); =20 /* * For devmap managed pages we need to catch refcount transition from @@ -1256,13 +1280,12 @@ static inline void put_page(struct page *page) * need to inform the device driver through callback. See * include/linux/memremap.h and HMM for details. */ - if (page_is_devmap_managed(page)) { - put_devmap_managed_page(page); + if (page_is_devmap_managed(&folio->page)) { + put_devmap_managed_page(&folio->page); return; } =20 - if (put_page_testzero(page)) - __put_page(page); + folio_put(folio); } =20 /* --=20 2.30.2