Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754361AbdFEQcn (ORCPT ); Mon, 5 Jun 2017 12:32:43 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60858 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753953AbdFEQcf (ORCPT ); Mon, 5 Jun 2017 12:32:35 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, James Morse , Punit Agrawal , Naoya Horiguchi , "Kirill A . Shutemov" , Andrew Morton , Linus Torvalds Subject: [PATCH 4.11 084/115] mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified Date: Mon, 5 Jun 2017 18:17:57 +0200 Message-Id: <20170605153100.805627066@linuxfoundation.org> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170605153056.650217313@linuxfoundation.org> References: <20170605153056.650217313@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4108 Lines: 120 4.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Morse commit 9a291a7c9428155e8e623e4a3989f8be47134df5 upstream. KVM uses get_user_pages() to resolve its stage2 faults. KVM sets the FOLL_HWPOISON flag causing faultin_page() to return -EHWPOISON when it finds a VM_FAULT_HWPOISON. KVM handles these hwpoison pages as a special case. (check_user_page_hwpoison()) When huge pages are involved, this doesn't work so well. get_user_pages() calls follow_hugetlb_page(), which stops early if it receives VM_FAULT_HWPOISON from hugetlb_fault(), eventually returning -EFAULT to the caller. The step to map this to -EHWPOISON based on the FOLL_ flags is missing. The hwpoison special case is skipped, and -EFAULT is returned to user-space, causing Qemu or kvmtool to exit. Instead, move this VM_FAULT_ to errno mapping code into a header file and use it from faultin_page() and follow_hugetlb_page(). With this, KVM works as expected. This isn't a problem for arm64 today as we haven't enabled MEMORY_FAILURE, but I can't see any reason this doesn't happen on x86 too, so I think this should be a fix. This doesn't apply earlier than stable's v4.11.1 due to all sorts of cleanup. [james.morse@arm.com: add vm_fault_to_errno() call to faultin_page()] suggested. Link: http://lkml.kernel.org/r/20170525171035.16359-1-james.morse@arm.com [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170524160900.28786-1-james.morse@arm.com Signed-off-by: James Morse Acked-by: Punit Agrawal Acked-by: Naoya Horiguchi Cc: "Kirill A . Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/mm.h | 11 +++++++++++ mm/gup.c | 20 ++++++++------------ mm/hugetlb.c | 5 +++++ 3 files changed, 24 insertions(+), 12 deletions(-) --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2315,6 +2315,17 @@ static inline struct page *follow_page(s #define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */ #define FOLL_COW 0x4000 /* internal GUP flag */ +static inline int vm_fault_to_errno(int vm_fault, int foll_flags) +{ + if (vm_fault & VM_FAULT_OOM) + return -ENOMEM; + if (vm_fault & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) + return (foll_flags & FOLL_HWPOISON) ? -EHWPOISON : -EFAULT; + if (vm_fault & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) + return -EFAULT; + return 0; +} + typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, --- a/mm/gup.c +++ b/mm/gup.c @@ -407,12 +407,10 @@ static int faultin_page(struct task_stru ret = handle_mm_fault(vma, address, fault_flags); if (ret & VM_FAULT_ERROR) { - if (ret & VM_FAULT_OOM) - return -ENOMEM; - if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) - return *flags & FOLL_HWPOISON ? -EHWPOISON : -EFAULT; - if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) - return -EFAULT; + int err = vm_fault_to_errno(ret, *flags); + + if (err) + return err; BUG(); } @@ -723,12 +721,10 @@ retry: ret = handle_mm_fault(vma, address, fault_flags); major |= ret & VM_FAULT_MAJOR; if (ret & VM_FAULT_ERROR) { - if (ret & VM_FAULT_OOM) - return -ENOMEM; - if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) - return -EHWPOISON; - if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) - return -EFAULT; + int err = vm_fault_to_errno(ret, 0); + + if (err) + return err; BUG(); } --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4170,6 +4170,11 @@ long follow_hugetlb_page(struct mm_struc } ret = hugetlb_fault(mm, vma, vaddr, fault_flags); if (ret & VM_FAULT_ERROR) { + int err = vm_fault_to_errno(ret, flags); + + if (err) + return err; + remainder = 0; break; }