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Thu, 18 Apr 2019 22:04:20 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1648D60851; Thu, 18 Apr 2019 22:04:17 +0000 (UTC) Date: Thu, 18 Apr 2019 18:04:15 -0400 From: Jerome Glisse To: Laurent Dufour Subject: Re: [PATCH v12 05/31] mm: prepare for FAULT_FLAG_SPECULATIVE Message-ID: <20190418220415.GE11645@redhat.com> References: <20190416134522.17540-1-ldufour@linux.ibm.com> <20190416134522.17540-6-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: <20190416134522.17540-6-ldufour@linux.ibm.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Thu, 18 Apr 2019 22:04:21 +0000 (UTC) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jack@suse.cz, sergey.senozhatsky.work@gmail.com, peterz@infradead.org, Will Deacon , mhocko@kernel.org, linux-mm@kvack.org, paulus@samba.org, Punit Agrawal , hpa@zytor.com, Michel Lespinasse , Alexei Starovoitov , Andrea Arcangeli , ak@linux.intel.com, Minchan Kim , aneesh.kumar@linux.ibm.com, x86@kernel.org, Matthew Wilcox , Daniel Jordan , Ingo Molnar , David Rientjes , paulmck@linux.vnet.ibm.com, Haiyan Song , npiggin@gmail.com, sj38.park@gmail.com, dave@stgolabs.net, kemi.wang@intel.com, kirill@shutemov.name, Thomas Gleixner , zhong jiang , Ganesh Mahendran , Yang Shi , Mike Rapoport , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , vinayak menon , akpm@linux-foundation.org, Tim Chen , haren@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Apr 16, 2019 at 03:44:56PM +0200, Laurent Dufour wrote: > From: Peter Zijlstra > > When speculating faults (without holding mmap_sem) we need to validate > that the vma against which we loaded pages is still valid when we're > ready to install the new PTE. > > Therefore, replace the pte_offset_map_lock() calls that (re)take the > PTL with pte_map_lock() which can fail in case we find the VMA changed > since we started the fault. > > Signed-off-by: Peter Zijlstra (Intel) > > [Port to 4.12 kernel] > [Remove the comment about the fault_env structure which has been > implemented as the vm_fault structure in the kernel] > [move pte_map_lock()'s definition upper in the file] > [move the define of FAULT_FLAG_SPECULATIVE later in the series] > [review error path in do_swap_page(), do_anonymous_page() and > wp_page_copy()] > Signed-off-by: Laurent Dufour Reviewed-by: Jérôme Glisse > --- > mm/memory.c | 87 +++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 58 insertions(+), 29 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index c6ddadd9d2b7..fc3698d13cb5 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_map_lock(struct vm_fault *vmf) I am not fan of the name maybe pte_offset_map_lock_if_valid() ? But that just a taste thing. So feel free to ignore this comment. > +{ > + vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, > + vmf->address, &vmf->ptl); > + return true; > +} > + > /* > * handle_pte_fault chooses page fault handler according to an entry which was > * read non-atomically. Before making any commitment, on those architectures