From patchwork Wed Sep 4 00:58:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11129111 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F18EC1399 for ; Wed, 4 Sep 2019 00:58:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C734921897 for ; Wed, 4 Sep 2019 00:58:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C734921897 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CFE8C6B0003; Tue, 3 Sep 2019 20:58:47 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id CAFD36B0006; Tue, 3 Sep 2019 20:58:47 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B9E516B0007; Tue, 3 Sep 2019 20:58:47 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0160.hostedemail.com [216.40.44.160]) by kanga.kvack.org (Postfix) with ESMTP id 998666B0003 for ; Tue, 3 Sep 2019 20:58:47 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 3CC9E906D for ; Wed, 4 Sep 2019 00:58:47 +0000 (UTC) X-FDA: 75895428294.08.match18_697c94f395707 X-Spam-Summary: 2,0,0,5125edf393c557de,d41d8cd98f00b204,justin.he@arm.com,:akpm@linux-foundation.org:willy@infradead.org:jglisse@redhat.com:rcampbell@nvidia.com:jgg@ziepe.ca:peterz@infradead.org:airlied@redhat.com:aneesh.kumar@linux.ibm.com:thellstrom@vmware.com:jrdr.linux@gmail.com::linux-kernel@vger.kernel.org:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:967:973:988:989:1042:1260:1261:1345:1437:1534:1543:1711:1730:1747:1777:1792:2393:2525:2559:2563:2682:2685:2693:2859:2901:2918:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3355:3865:3866:3867:3868:3870:3871:3872:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4250:4321:5007:6117:6119:6261:6671:6737:7208:7903:8634:8660:9025:9113:10004:11026:11473:11658:11914:12043:12048:12295:12296:12297:12438:12555:12679:12895:12986:13007:13148:13161:13221:13229:13230:14096:14181:14394:14721:21080:21451:21627:21772:21795:30003:30051:30054:30075,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-62.14.0.100 64 .201.201 X-HE-Tag: match18_697c94f395707 X-Filterd-Recvd-Size: 4995 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Wed, 4 Sep 2019 00:58:44 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 76655344; Tue, 3 Sep 2019 17:58:43 -0700 (PDT) Received: from entos-thunderx2-02.shanghai.arm.com (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 91F0A3F246; Tue, 3 Sep 2019 17:58:40 -0700 (PDT) From: Jia He To: Andrew Morton , Matthew Wilcox , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ralph Campbell , Jason Gunthorpe , Peter Zijlstra , Dave Airlie , "Aneesh Kumar K.V" , Thomas Hellstrom , Souptick Joarder , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Jia He Subject: [PATCH] mm: fix double page fault on arm64 if PTE_AF is cleared Date: Wed, 4 Sep 2019 08:58:31 +0800 Message-Id: <20190904005831.153934-1-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 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: When we tested pmdk unit test [1] vmmalloc_fork TEST1 in arm64 guest, there will be a double page fault in __copy_from_user_inatomic of cow_user_page. Below call trace is from arm64 do_page_fault for debugging purpose [ 110.016195] Call trace: [ 110.016826] do_page_fault+0x5a4/0x690 [ 110.017812] do_mem_abort+0x50/0xb0 [ 110.018726] el1_da+0x20/0xc4 [ 110.019492] __arch_copy_from_user+0x180/0x280 [ 110.020646] do_wp_page+0xb0/0x860 [ 110.021517] __handle_mm_fault+0x994/0x1338 [ 110.022606] handle_mm_fault+0xe8/0x180 [ 110.023584] do_page_fault+0x240/0x690 [ 110.024535] do_mem_abort+0x50/0xb0 [ 110.025423] el0_da+0x20/0x24 The pte info before __copy_from_user_inatomic is(PTE_AF is cleared): [ffff9b007000] pgd=000000023d4f8003, pud=000000023da9b003, pmd=000000023d4b3003, pte=360000298607bd3 The keypoint is: we don't always have a hardware-managed access flag on arm64. The root cause is in copy_one_pte, it will clear the PTE_AF for COW pages. Generally, when it is accessed by user, the COW pages will be set as accessed(PTE_AF bit on arm64) by hardware if hardware feature is supported. But on some arm64 platforms, the PTE_AF needs to be set by software. This patch fix it by calling pte_mkyoung. Also, the parameter is changed because vmf should be passed to cow_user_page() [1] https://github.com/pmem/pmdk/tree/master/src/test/vmmalloc_fork Reported-by: Yibo Cai Signed-off-by: Jia He --- mm/memory.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index e2bb51b6242e..b1f9ace2e943 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2140,7 +2140,8 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, return same; } -static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) +static inline void cow_user_page(struct page *dst, struct page *src, + struct vm_fault *vmf) { debug_dma_assert_idle(src); @@ -2152,20 +2153,30 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo */ if (unlikely(!src)) { void *kaddr = kmap_atomic(dst); - void __user *uaddr = (void __user *)(va & PAGE_MASK); + void __user *uaddr = (void __user *)(vmf->address & PAGE_MASK); + pte_t entry; /* * This really shouldn't fail, because the page is there * in the page tables. But it might just be unreadable, * in which case we just give up and fill the result with - * zeroes. + * zeroes. If PTE_AF is cleared on arm64, it might + * cause double page fault here. so makes pte young here */ + if (!pte_young(vmf->orig_pte)) { + entry = pte_mkyoung(vmf->orig_pte); + if (ptep_set_access_flags(vmf->vma, vmf->address, + vmf->pte, entry, vmf->flags & FAULT_FLAG_WRITE)) + update_mmu_cache(vmf->vma, vmf->address, + vmf->pte); + } + if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) clear_page(kaddr); kunmap_atomic(kaddr); flush_dcache_page(dst); } else - copy_user_highpage(dst, src, va, vma); + copy_user_highpage(dst, src, vmf->address, vmf->vma); } static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) @@ -2318,7 +2329,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) vmf->address); if (!new_page) goto oom; - cow_user_page(new_page, old_page, vmf->address, vma); + cow_user_page(new_page, old_page, vmf); } if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))