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[58.6.239.121]) by smtp.gmail.com with ESMTPSA id x67sm19601345pfx.144.2021.03.16.23.47.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 23:47:44 -0700 (PDT) From: Nicholas Piggin To: linux-mm@kvack.org Cc: Nicholas Piggin , Peter Zijlstra Subject: [PATCH v2 2/3] mm: add page_cpupid_reset_last atomic variant Date: Wed, 17 Mar 2021 16:47:29 +1000 Message-Id: <20210317064730.546507-2-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210317064730.546507-1-npiggin@gmail.com> References: <20210317064730.546507-1-npiggin@gmail.com> MIME-Version: 1.0 X-Stat-Signature: fbi5uq154u451y8qdanouoawepude66d X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 2E61FA0009D5 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=mail-pl1-f170.google.com; client-ip=209.85.214.170 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615963666-187557 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: This can be used when there is concurrency on the struct page. If cpupid is not in page flags, it can use a store. Use this to replace the open-coded reset in wp_page_reuse. Signed-off-by: Nicholas Piggin --- include/linux/mm.h | 15 +++++++++++++++ mm/memory.c | 2 +- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 086ab710383f..2524553ea898 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1400,6 +1400,11 @@ static inline void __page_cpupid_reset_last(struct page *page) { page->_last_cpupid = -1 & LAST_CPUPID_MASK; } + +static inline void page_cpupid_reset_last(struct page *page) +{ + WRITE_ONCE(page->_last_cpupid, -1 & LAST_CPUPID_MASK); +} #else static inline int page_cpupid_last(struct page *page) { @@ -1412,6 +1417,12 @@ static inline void __page_cpupid_reset_last(struct page *page) { page->flags |= LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT; } + +static inline void page_cpupid_reset_last(struct page *page) +{ + page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); +} + #endif /* LAST_CPUPID_NOT_IN_PAGE_FLAGS */ #else /* !CONFIG_NUMA_BALANCING */ static inline int page_cpupid_xchg_last(struct page *page, int cpupid) @@ -1453,6 +1464,10 @@ static inline void __page_cpupid_reset_last(struct page *page) { } +static inline void page_cpupid_reset_last(struct page *page) +{ +} + static inline bool cpupid_match_pid(struct task_struct *task, int cpupid) { return false; diff --git a/mm/memory.c b/mm/memory.c index 5efa07fb6cdc..bb37dc0f4dac 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2804,7 +2804,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf) * unrelated process. */ if (page) - page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); + page_cpupid_reset_last(page); flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); entry = pte_mkyoung(vmf->orig_pte);