From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752068AbdBNFuQ (ORCPT ); Tue, 14 Feb 2017 00:50:16 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35793 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750716AbdBNFuO (ORCPT ); Tue, 14 Feb 2017 00:50:14 -0500 From: Michael Ellerman To: "Aneesh Kumar K.V" , akpm@linux-foundation.org, Rik van Riel , Mel Gorman , paulus@ozlabs.org, benh@kernel.crashing.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Subject: Re: [PATCH V2 1/2] mm/autonuma: Let architecture override how the write bit should be stashed in a protnone pte. In-Reply-To: <1487050314-3892-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1487050314-3892-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1487050314-3892-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Tue, 14 Feb 2017 16:49:04 +1100 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17021405-0016-0000-0000-000002193BCD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17021405-0017-0000-0000-000006694332 Message-Id: <87poilmien.fsf@concordia.ellerman.id.au> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-02-14_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702140061 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Aneesh Kumar K.V" writes: > Autonuma preserves the write permission across numa fault to avoid taking > a writefault after a numa fault (Commit: b191f9b106ea " mm: numa: preserve PTE > write permissions across a NUMA hinting fault"). Architecture can implement > protnone in different ways and some may choose to implement that by clearing Read/ > Write/Exec bit of pte. Setting the write bit on such pte can result in wrong > behaviour. Fix this up by allowing arch to override how to save the write bit > on a protnone pte. This is pretty obviously a nop on arches that don't implement the new hooks, but it'd still be good to get an ack from someone in mm land before I merge it. cheers > Acked-By: Michael Neuling > Signed-off-by: Aneesh Kumar K.V > --- > include/asm-generic/pgtable.h | 16 ++++++++++++++++ > mm/huge_memory.c | 4 ++-- > mm/memory.c | 2 +- > mm/mprotect.c | 4 ++-- > 4 files changed, 21 insertions(+), 5 deletions(-) > > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > index 18af2bcefe6a..b6f3a8a4b738 100644 > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -192,6 +192,22 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres > } > #endif > > +#ifndef pte_savedwrite > +#define pte_savedwrite pte_write > +#endif > + > +#ifndef pte_mk_savedwrite > +#define pte_mk_savedwrite pte_mkwrite > +#endif > + > +#ifndef pmd_savedwrite > +#define pmd_savedwrite pmd_write > +#endif > + > +#ifndef pmd_mk_savedwrite > +#define pmd_mk_savedwrite pmd_mkwrite > +#endif > + > #ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > static inline void pmdp_set_wrprotect(struct mm_struct *mm, > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 9a6bd6c8d55a..2f0f855ec911 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1300,7 +1300,7 @@ int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) > goto out; > clear_pmdnuma: > BUG_ON(!PageLocked(page)); > - was_writable = pmd_write(pmd); > + was_writable = pmd_savedwrite(pmd); > pmd = pmd_modify(pmd, vma->vm_page_prot); > pmd = pmd_mkyoung(pmd); > if (was_writable) > @@ -1555,7 +1555,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, > entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); > entry = pmd_modify(entry, newprot); > if (preserve_write) > - entry = pmd_mkwrite(entry); > + entry = pmd_mk_savedwrite(entry); > ret = HPAGE_PMD_NR; > set_pmd_at(mm, addr, pmd, entry); > BUG_ON(vma_is_anonymous(vma) && !preserve_write && > diff --git a/mm/memory.c b/mm/memory.c > index e78bf72f30dd..88c24f89d6d3 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3388,7 +3388,7 @@ static int do_numa_page(struct vm_fault *vmf) > int target_nid; > bool migrated = false; > pte_t pte; > - bool was_writable = pte_write(vmf->orig_pte); > + bool was_writable = pte_savedwrite(vmf->orig_pte); > int flags = 0; > > /* > diff --git a/mm/mprotect.c b/mm/mprotect.c > index f9c07f54dd62..15f5c174a7c1 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -113,13 +113,13 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, > ptent = ptep_modify_prot_start(mm, addr, pte); > ptent = pte_modify(ptent, newprot); > if (preserve_write) > - ptent = pte_mkwrite(ptent); > + ptent = pte_mk_savedwrite(ptent); > > /* Avoid taking write faults for known dirty pages */ > if (dirty_accountable && pte_dirty(ptent) && > (pte_soft_dirty(ptent) || > !(vma->vm_flags & VM_SOFTDIRTY))) { > - ptent = pte_mkwrite(ptent); > + ptent = pte_mk_savedwrite(ptent); > } > ptep_modify_prot_commit(mm, addr, pte, ptent); > pages++; > -- > 2.7.4