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Sun, 8 Aug 2021 23:56:19 +0000 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sun, 8 Aug 2021 23:56:18 +0000 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sun, 8 Aug 2021 23:50:26 +0000 Received: from sandstorm.attlocal.net (172.20.187.5) by mail.nvidia.com (172.20.187.12) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sun, 8 Aug 2021 23:50:26 +0000 From: John Hubbard To: Andrew Morton , Matthew Wilcox CC: LKML , , John Hubbard Subject: [PATCH 3/3] mm/gup: refactor and simplify try_get_page() Date: Sun, 8 Aug 2021 16:50:18 -0700 Message-ID: <20210808235018.1924918-4-jhubbard@nvidia.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210808235018.1924918-1-jhubbard@nvidia.com> References: <20210808235018.1924918-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: c67cdf41-6ee7-4d3c-a6ea-08d95ac81e07 X-MS-TrafficTypeDiagnostic: MN2PR12MB4064: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:5516; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Aug 2021 23:56:19.2383 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c67cdf41-6ee7-4d3c-a6ea-08d95ac81e07 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.35];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT010.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4064 Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=QAjiZNJb; spf=none (imf02.hostedemail.com: domain of jhubbard@nvidia.com has no SPF policy when checking 40.107.243.42) smtp.mailfrom=jhubbard@nvidia.com; dmarc=pass (policy=quarantine) header.from=nvidia.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D0B8770037B4 X-Stat-Signature: 6hcducf8dddi3eqa3wrgcddz9b87uu7s X-HE-Tag: 1628466980-391028 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: try_get_page() is very similar to try_get_compound_head(), and in fact try_get_page() has fallen a little behind in terms of maintenance: try_get_compound_head() handles speculative page references more thoroughly. Change try_get_page() so that it is implemented in terms of try_get_compound_head(), but without changing try_get_page()'s API contract. Signed-off-by: John Hubbard --- include/linux/mm.h | 11 ++++++----- mm/gup.c | 2 +- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index ce8fc0fd6d6e..92d3b37357d5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1207,14 +1207,15 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags); __maybe_unused struct page *try_grab_compound_head(struct page *page, int refs, unsigned int flags); +struct page *try_get_compound_head(struct page *page, int refs); +/* + * This has the same functionality as try_get_compound_head(), just with a + * slightly different API. + */ static inline __must_check bool try_get_page(struct page *page) { - page = compound_head(page); - if (WARN_ON_ONCE(page_ref_count(page) <= 0)) - return false; - page_ref_inc(page); - return true; + return try_get_compound_head(page, 1) != NULL; } /** diff --git a/mm/gup.c b/mm/gup.c index 4be6f060fa0b..ba75906ba7f7 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -66,7 +66,7 @@ static void put_page_refs(struct page *page, int refs) * Return the compound head page with ref appropriately incremented, * or NULL if that failed. */ -static inline struct page *try_get_compound_head(struct page *page, int refs) +struct page *try_get_compound_head(struct page *page, int refs) { struct page *head = compound_head(page);