Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757414AbbKRXuc (ORCPT ); Wed, 18 Nov 2015 18:50:32 -0500 Received: from e06smtp08.uk.ibm.com ([195.75.94.104]:58393 "EHLO e06smtp08.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757355AbbKRXuF (ORCPT ); Wed, 18 Nov 2015 18:50:05 -0500 X-IBM-Helo: d06dlp01.portsmouth.uk.ibm.com X-IBM-MailFrom: dingel@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-s390@vger.kernel.org From: Dominik Dingel To: linux-s390@vger.kernel.org, linux-mm@kvack.org Cc: Andrew Morton , "Kirill A. Shutemov" , Andrea Arcangeli , David Rientjes , Eric B Munson , Naoya Horiguchi , Mel Gorman , Martin Schwidefsky , Heiko Carstens , Dominik Dingel , Christian Borntraeger , Paolo Bonzini , "Jason J. Herne" , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] s390/mm: allow gmap code to retry on faulting in guest memory Date: Thu, 19 Nov 2015 00:49:58 +0100 Message-Id: <1447890598-56860-3-git-send-email-dingel@linux.vnet.ibm.com> X-Mailer: git-send-email 2.3.9 In-Reply-To: <1447890598-56860-1-git-send-email-dingel@linux.vnet.ibm.com> References: <1447890598-56860-1-git-send-email-dingel@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15111823-0033-0000-0000-000004D197E3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3086 Lines: 99 The userfaultfd does need FAULT_FLAG_ALLOW_RETRY to not return VM_FAULT_SIGBUS. So we improve the gmap code to handle one VM_FAULT_RETRY. Signed-off-by: Dominik Dingel --- arch/s390/mm/pgtable.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 54ef3bc..8a0025d 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -577,15 +577,22 @@ int gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fault_flags) { unsigned long vmaddr; - int rc; + int rc, fault; + fault_flags |= FAULT_FLAG_ALLOW_RETRY; +retry: down_read(&gmap->mm->mmap_sem); vmaddr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(vmaddr)) { rc = vmaddr; goto out_up; } - if (fixup_user_fault(current, gmap->mm, vmaddr, fault_flags)) { + fault = fixup_user_fault(current, gmap->mm, vmaddr, fault_flags); + if (fault & VM_FAULT_RETRY) { + fault_flags &= ~FAULT_FLAG_ALLOW_RETRY; + fault_flags |= FAULT_FLAG_TRIED; + goto retry; + } else if (fault) { rc = -EFAULT; goto out_up; } @@ -717,10 +724,13 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len) spinlock_t *ptl; pte_t *ptep, entry; pgste_t pgste; + int fault, fault_flags; int rc = 0; + fault_flags = FAULT_FLAG_WRITE | FAULT_FLAG_ALLOW_RETRY; if ((gaddr & ~PAGE_MASK) || (len & ~PAGE_MASK)) return -EINVAL; +retry: down_read(&gmap->mm->mmap_sem); while (len) { /* Convert gmap address and connect the page tables */ @@ -730,7 +740,12 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len) break; } /* Get the page mapped */ - if (fixup_user_fault(current, gmap->mm, addr, FAULT_FLAG_WRITE)) { + fault = fixup_user_fault(current, gmap->mm, addr, fault_flags); + if (fault & VM_FAULT_RETRY) { + fault_flags &= ~FAULT_FLAG_ALLOW_RETRY; + fault_flags |= FAULT_FLAG_TRIED; + goto retry; + } else if (fault) { rc = -EFAULT; break; } @@ -794,7 +809,9 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr, spinlock_t *ptl; pgste_t old, new; pte_t *ptep; + int fault, fault_flags; + fault_flags = FAULT_FLAG_WRITE | FAULT_FLAG_ALLOW_RETRY; down_read(&mm->mmap_sem); retry: ptep = get_locked_pte(mm, addr, &ptl); @@ -805,10 +822,13 @@ retry: if (!(pte_val(*ptep) & _PAGE_INVALID) && (pte_val(*ptep) & _PAGE_PROTECT)) { pte_unmap_unlock(ptep, ptl); - if (fixup_user_fault(current, mm, addr, FAULT_FLAG_WRITE)) { + fault = fixup_user_fault(current, mm, addr, fault_flags); + if (fault && !(fault & VM_FAULT_RETRY)) { up_read(&mm->mmap_sem); return -EFAULT; } + fault_flags &= ~FAULT_FLAG_ALLOW_RETRY; + fault_flags |= FAULT_FLAG_TRIED; goto retry; } -- 2.3.9 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/