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[209.85.220.65]) by mx.google.com with SMTPS id cu6sor44426656pjb.22.2019.07.21.08.58.30 for (Google Transport Security); Sun, 21 Jul 2019 08:58:30 -0700 (PDT) Received-SPF: pass (google.com: domain of linux.bhar@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="ODLroZ/h"; spf=pass (google.com: domain of linux.bhar@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=linux.bhar@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=mu8trQVZC3rHCOtMYrCUpgRKCETCP3JlFKLgFP5GMsg=; b=ODLroZ/h+hP6Y33PcgSXD4q2Uc8RcP/LdSQozj6vnDx90z1Mq6K/foEe5nz7ZE2BPd yYZAMSLyYG3vQ0iOmeXcDLNnWfNQH4g6AMONx5mDjWIdel6bpziU1NAHYdyK2pZ378Rr FZ2ZeYBK/Uor03e7IT/JubBVBKBTHhPcV8cRRS95AnmkWrOA5HCwpl5IfUJ32bAZkYFy kLT059ALWFeHtBbDtT1ZXSm/q583gn6n+Z++Kw7Pm61/vOy0/vDZ6m9Jy6b1Uk8C8yb2 wMujseQCu+jXWT0qW/n5t4vm67DuuywYUODpEzZ8ow7y4QxZPfogWyGgMHcWonCunkUn phfg== X-Google-Smtp-Source: APXvYqwC3lbzN6ZeQmPUeK90Wp81J3UzSILb/l6kA0SmEh/tiLeanHZIQoe+bvHFOO1ZCx7hgtXRQg== X-Received: by 2002:a17:90a:bf08:: with SMTP id c8mr71922342pjs.75.1563724710070; Sun, 21 Jul 2019 08:58:30 -0700 (PDT) Received: from bharath12345-Inspiron-5559 ([103.110.42.34]) by smtp.gmail.com with ESMTPSA id w22sm38827754pfi.175.2019.07.21.08.58.28 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 21 Jul 2019 08:58:29 -0700 (PDT) From: Bharath Vedartham To: arnd@arndb.de, sivanich@sgi.com, gregkh@linuxfoundation.org Cc: ira.weiny@intel.com, jhubbard@nvidia.com, jglisse@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Bharath Vedartham Subject: [PATCH 3/3] sgi-gru: Use __get_user_pages_fast in atomic_pte_lookup Date: Sun, 21 Jul 2019 21:28:05 +0530 Message-Id: <1563724685-6540-4-git-send-email-linux.bhar@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1563724685-6540-1-git-send-email-linux.bhar@gmail.com> References: <1563724685-6540-1-git-send-email-linux.bhar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: *pte_lookup functions get the physical address for a given virtual address by getting a physical page using gup and use page_to_phys to get the physical address. Currently, atomic_pte_lookup manually walks the page tables. If this function fails to get a physical page, it will fall back too non_atomic_pte_lookup to get a physical page which uses the slow gup path to get the physical page. Instead of manually walking the page tables use __get_user_pages_fast which does the same thing and it does not fall back to the slow gup path. This is largely inspired from kvm code. kvm uses __get_user_pages_fast in hva_to_pfn_fast function which can run in an atomic context. Cc: Ira Weiny Cc: John Hubbard Cc: Jérôme Glisse Cc: Greg Kroah-Hartman Cc: Dimitri Sivanich Cc: Arnd Bergmann Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Bharath Vedartham --- drivers/misc/sgi-gru/grufault.c | 39 +++++---------------------------------- 1 file changed, 5 insertions(+), 34 deletions(-) diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index 75108d2..121c9a4 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -202,46 +202,17 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma, static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr, int write, unsigned long *paddr, int *pageshift) { - pgd_t *pgdp; - p4d_t *p4dp; - pud_t *pudp; - pmd_t *pmdp; - pte_t pte; - - pgdp = pgd_offset(vma->vm_mm, vaddr); - if (unlikely(pgd_none(*pgdp))) - goto err; - - p4dp = p4d_offset(pgdp, vaddr); - if (unlikely(p4d_none(*p4dp))) - goto err; - - pudp = pud_offset(p4dp, vaddr); - if (unlikely(pud_none(*pudp))) - goto err; + struct page *page; - pmdp = pmd_offset(pudp, vaddr); - if (unlikely(pmd_none(*pmdp))) - goto err; -#ifdef CONFIG_X86_64 - if (unlikely(pmd_large(*pmdp))) - pte = *(pte_t *) pmdp; - else -#endif - pte = *pte_offset_kernel(pmdp, vaddr); + *pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT; - if (unlikely(!pte_present(pte) || - (write && (!pte_write(pte) || !pte_dirty(pte))))) + if (!__get_user_pages_fast(vaddr, 1, write, &page)) return 1; - *paddr = pte_pfn(pte) << PAGE_SHIFT; - - *pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT; + *paddr = page_to_phys(page); + put_user_page(page); return 0; - -err: - return 1; } static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, -- 2.7.4