From patchwork Fri Sep 20 13:54:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin He X-Patchwork-Id: 11154485 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 F1D301599 for ; Fri, 20 Sep 2019 13:55:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C854E206C2 for ; Fri, 20 Sep 2019 13:55:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C854E206C2 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 EA3316B0008; Fri, 20 Sep 2019 09:55:02 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id E7A1C6B000A; Fri, 20 Sep 2019 09:55:02 -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 DB7886B000C; Fri, 20 Sep 2019 09:55:02 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0005.hostedemail.com [216.40.44.5]) by kanga.kvack.org (Postfix) with ESMTP id BC9266B0008 for ; Fri, 20 Sep 2019 09:55:02 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 4E74BBF17 for ; Fri, 20 Sep 2019 13:55:02 +0000 (UTC) X-FDA: 75955445244.29.lift25_65dcac6ee545c X-Spam-Summary: 10,1,0,7e33cfe9679976f7,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:punitagrawal@gmail.com:anshuman.khandual@arm.com:avanbrunt@nvidia.com:robin.murphy@arm.com:tglx@linutronix.de:akpm@linux-foundation.org:jglisse@redhat.com:rcampbell@nvidia.com:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1261:1345:1359:1437:1534:1541:1711:1730:1747:1777:1792:2393:2559:2562:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3872:4250:5007:6119:6261:6737:6742:7903:8634:10004:11026:11473:11657:11658:11914:12043:12048:12296:12297:12438:12555:12895:13069:13221:13229:13311:13357:13523:13524:14096:14181:14384:14394:14721:21080:21451:21627:30054:30064,0,RBL:217.140.110.172:@arm.com:.lbl8.mai lshell.n X-HE-Tag: lift25_65dcac6ee545c X-Filterd-Recvd-Size: 2889 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Sep 2019 13:54:59 +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 EB45B1597; Fri, 20 Sep 2019 06:54:57 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 78A403F67D; Fri, 20 Sep 2019 06:54:53 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v7 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Date: Fri, 20 Sep 2019 21:54:35 +0800 Message-Id: <20190920135437.25622-2-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190920135437.25622-1-justin.he@arm.com> References: <20190920135437.25622-1-justin.he@arm.com> 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: We unconditionally set the HW_AFDBM capability and only enable it on CPUs which really have the feature. But sometimes we need to know whether this cpu has the capability of HW AF. So decouple AF from DBM by new helper cpu_has_hw_af(). Reported-by: kbuild test robot Suggested-by: Suzuki Poulose Signed-off-by: Jia He --- arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index c96ffa4722d3..46caf934ba4e 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -667,6 +667,16 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) default: return CONFIG_ARM64_PA_BITS; } } + +/* Decouple AF from AFDBM. */ +static inline bool cpu_has_hw_af(void) +{ + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; + + return false; +} + #endif /* __ASSEMBLY__ */ #endif From patchwork Fri Sep 20 13:54:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin He X-Patchwork-Id: 11154487 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 6F35B1599 for ; Fri, 20 Sep 2019 13:55:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 469A62054F for ; Fri, 20 Sep 2019 13:55:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 469A62054F 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 247586B000A; Fri, 20 Sep 2019 09:55:06 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 21E156B000C; Fri, 20 Sep 2019 09:55:06 -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 15A7B6B000D; Fri, 20 Sep 2019 09:55:06 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0214.hostedemail.com [216.40.44.214]) by kanga.kvack.org (Postfix) with ESMTP id ECE5A6B000A for ; Fri, 20 Sep 2019 09:55:05 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id A8F4B6D7C for ; Fri, 20 Sep 2019 13:55:05 +0000 (UTC) X-FDA: 75955445370.29.card23_66978fd025a22 X-Spam-Summary: 2,0,0,c636c6e16beea3d1,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:punitagrawal@gmail.com:anshuman.khandual@arm.com:avanbrunt@nvidia.com:robin.murphy@arm.com:tglx@linutronix.de:akpm@linux-foundation.org:jglisse@redhat.com:rcampbell@nvidia.com:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1261:1345:1359:1437:1534:1541:1711:1730:1747:1777:1792:2393:2559:2562:2693:2901:3138:3139:3140:3141:3142:3352:3865:3867:3868:3871:3872:3874:4321:5007:6119:6261:6737:6742:7903:8634:10004:11026:11657:11658:11914:12043:12048:12114:12297:12438:12555:12895:13069:13161:13229:13311:13357:14096:14181:14384:14394:14721:21080:21451:21627:30054,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net -62.2.0. X-HE-Tag: card23_66978fd025a22 X-Filterd-Recvd-Size: 3164 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Sep 2019 13:55:04 +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 B7B5C1570; Fri, 20 Sep 2019 06:55:02 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4DD873F67D; Fri, 20 Sep 2019 06:54:58 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v7 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Fri, 20 Sep 2019 21:54:36 +0800 Message-Id: <20190920135437.25622-3-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190920135437.25622-1-justin.he@arm.com> References: <20190920135437.25622-1-justin.he@arm.com> 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 arm64 without hardware Access Flag, copying fromuser will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He --- arch/arm64/include/asm/pgtable.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..4a9939615e41 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -868,6 +868,18 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying fromuser will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. we don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ From patchwork Fri Sep 20 13:54:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin He X-Patchwork-Id: 11154489 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 D41041599 for ; Fri, 20 Sep 2019 13:55:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A1CC42054F for ; Fri, 20 Sep 2019 13:55:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1CC42054F 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 BE3E46B000C; Fri, 20 Sep 2019 09:55:10 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id B938F6B000D; Fri, 20 Sep 2019 09:55:10 -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 AAA196B000E; Fri, 20 Sep 2019 09:55:10 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0045.hostedemail.com [216.40.44.45]) by kanga.kvack.org (Postfix) with ESMTP id 8A8ED6B000C for ; Fri, 20 Sep 2019 09:55:10 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 3C20A181AC9B4 for ; Fri, 20 Sep 2019 13:55:10 +0000 (UTC) X-FDA: 75955445580.17.jump60_673fad4e02751 X-Spam-Summary: 2,0,0,042412525cc34a40,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:punitagrawal@gmail.com:anshuman.khandual@arm.com:avanbrunt@nvidia.com:robin.murphy@arm.com:tglx@linutronix.de:akpm@linux-foundation.org:jglisse@redhat.com:rcampbell@nvidia.com:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:2:41:355:379:541:800:960:967:973:988:989:1042:1260:1261:1345:1359:1437:1535:1605:1606:1730:1747:1777:1792:2393:2525:2559:2563:2682:2685:2693:2859:2901:2918:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4117:4321:4605:5007:6117:6119:6261:6671:6737:6742:7208:7903:8634:8660:9025:10004:11026:11473:11658:11914:12043:1204 8:12291: X-HE-Tag: jump60_673fad4e02751 X-Filterd-Recvd-Size: 6945 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Sep 2019 13:55:09 +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 85C741597; Fri, 20 Sep 2019 06:55:07 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 1A7653F67D; Fri, 20 Sep 2019 06:55:02 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v7 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Date: Fri, 20 Sep 2019 21:54:37 +0800 Message-Id: <20190920135437.25622-4-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190920135437.25622-1-justin.he@arm.com> References: <20190920135437.25622-1-justin.he@arm.com> 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 As told by Catalin: "On arm64 without hardware Access Flag, copying from user will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64." This patch fix it by calling pte_mkyoung. Also, the parameter is changed because vmf should be passed to cow_user_page() Add a WARN_ON_ONCE when __copy_from_user_inatomic() returns error in case there can be some obscure use-case.(by Kirill) [1] https://github.com/pmem/pmdk/tree/master/src/test/vmmalloc_fork Reported-by: Yibo Cai Signed-off-by: Jia He Acked-by: Kirill A. Shutemov --- mm/memory.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 61 insertions(+), 6 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index e2bb51b6242e..3e39e40fee87 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -118,6 +118,13 @@ int randomize_va_space __read_mostly = 2; #endif +#ifndef arch_faults_on_old_pte +static inline bool arch_faults_on_old_pte(void) +{ + return false; +} +#endif + static int __init disable_randmaps(char *s) { randomize_va_space = 0; @@ -2140,8 +2147,13 @@ 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 int cow_user_page(struct page *dst, struct page *src, + struct vm_fault *vmf) { + struct vm_area_struct *vma = vmf->vma; + struct mm_struct *mm = vma->vm_mm; + unsigned long addr = vmf->address; + debug_dma_assert_idle(src); /* @@ -2151,21 +2163,53 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo * fails, we just zero-fill it. Live with it. */ if (unlikely(!src)) { - void *kaddr = kmap_atomic(dst); - void __user *uaddr = (void __user *)(va & PAGE_MASK); + void *kaddr; + pte_t entry; + void __user *uaddr = (void __user *)(addr & PAGE_MASK); + /* On architectures with software "accessed" bits, we would + * take a double page fault, so mark it accessed here. + */ + if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) { + vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, + &vmf->ptl); + if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { + entry = pte_mkyoung(vmf->orig_pte); + if (ptep_set_access_flags(vma, addr, + vmf->pte, entry, 0)) + update_mmu_cache(vma, addr, vmf->pte); + } else { + /* Other thread has already handled the fault + * and we don't need to do anything. If it's + * not the case, the fault will be triggered + * again on the same address. + */ + pte_unmap_unlock(vmf->pte, vmf->ptl); + return -1; + } + pte_unmap_unlock(vmf->pte, vmf->ptl); + } + + kaddr = kmap_atomic(dst); /* * 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. */ - if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) + if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { + /* Give a warn in case there can be some obscure + * use-case + */ + WARN_ON_ONCE(1); clear_page(kaddr); + } kunmap_atomic(kaddr); flush_dcache_page(dst); } else - copy_user_highpage(dst, src, va, vma); + copy_user_highpage(dst, src, addr, vma); + + return 0; } static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) @@ -2318,7 +2362,18 @@ 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); + + if (cow_user_page(new_page, old_page, vmf)) { + /* COW failed, if the fault was solved by other, + * it's fine. If not, userspace would re-fault on + * the same address and we will handle the fault + * from the second attempt. + */ + put_page(new_page); + if (old_page) + put_page(old_page); + return 0; + } } if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))