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[209.132.183.28]) by mx.google.com with ESMTPS id d28si2201393qtb.275.2019.04.18.15.05.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Apr 2019 15:05:52 -0700 (PDT) Received-SPF: pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F3EE7301EA88; Thu, 18 Apr 2019 22:05:50 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 46F5A600C5; Thu, 18 Apr 2019 22:05:47 +0000 (UTC) Date: Thu, 18 Apr 2019 18:05:45 -0400 From: Jerome Glisse To: Laurent Dufour Cc: akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , aneesh.kumar@linux.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , sergey.senozhatsky.work@gmail.com, Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, Daniel Jordan , David Rientjes , Ganesh Mahendran , Minchan Kim , Punit Agrawal , vinayak menon , Yang Shi , zhong jiang , Haiyan Song , Balbir Singh , sj38.park@gmail.com, Michel Lespinasse , Mike Rapoport , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, npiggin@gmail.com, paulmck@linux.vnet.ibm.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: Re: [PATCH v12 06/31] mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE Message-ID: <20190418220545.GF11645@redhat.com> References: <20190416134522.17540-1-ldufour@linux.ibm.com> <20190416134522.17540-7-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190416134522.17540-7-ldufour@linux.ibm.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Thu, 18 Apr 2019 22:05:51 +0000 (UTC) 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: On Tue, Apr 16, 2019 at 03:44:57PM +0200, Laurent Dufour wrote: > When handling page fault without holding the mmap_sem the fetch of the > pte lock pointer and the locking will have to be done while ensuring > that the VMA is not touched in our back. > > So move the fetch and locking operations in a dedicated function. > > Signed-off-by: Laurent Dufour Reviewed-by: Jérôme Glisse > --- > mm/memory.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index fc3698d13cb5..221ccdf34991 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2073,6 +2073,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, > } > EXPORT_SYMBOL_GPL(apply_to_page_range); > > +static inline bool pte_spinlock(struct vm_fault *vmf) > +{ > + vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); > + spin_lock(vmf->ptl); > + return true; > +} > + > static inline bool pte_map_lock(struct vm_fault *vmf) > { > vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, > @@ -3656,8 +3663,8 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > * validation through pte_unmap_same(). It's of NUMA type but > * the pfn may be screwed if the read is non atomic. > */ > - vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); > - spin_lock(vmf->ptl); > + if (!pte_spinlock(vmf)) > + return VM_FAULT_RETRY; > if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { > pte_unmap_unlock(vmf->pte, vmf->ptl); > goto out; > @@ -3850,8 +3857,8 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) > if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) > return do_numa_page(vmf); > > - vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); > - spin_lock(vmf->ptl); > + if (!pte_spinlock(vmf)) > + return VM_FAULT_RETRY; > entry = vmf->orig_pte; > if (unlikely(!pte_same(*vmf->pte, entry))) > goto unlock; > -- > 2.21.0 >