From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xYKz82HZKzDrLd for ; Fri, 18 Aug 2017 08:05:40 +1000 (AEST) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7HM5UAI100614 for ; Thu, 17 Aug 2017 18:05:38 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2cdc4r8p9x-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 17 Aug 2017 18:05:38 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 17 Aug 2017 23:05:36 +0100 From: Laurent Dufour To: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v2 01/20] mm: Dont assume page-table invariance during faults Date: Fri, 18 Aug 2017 00:05:00 +0200 In-Reply-To: <1503007519-26777-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1503007519-26777-1-git-send-email-ldufour@linux.vnet.ibm.com> Message-Id: <1503007519-26777-2-git-send-email-ldufour@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Peter Zijlstra One of the side effects of speculating on faults (without holding mmap_sem) is that we can race with free_pgtables() and therefore we cannot assume the page-tables will stick around. Remove the reliance on the pte pointer. Signed-off-by: Peter Zijlstra (Intel) --- mm/memory.c | 27 --------------------------- 1 file changed, 27 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index e158f7ac6730..36609c082256 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2131,30 +2131,6 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, } EXPORT_SYMBOL_GPL(apply_to_page_range); -/* - * handle_pte_fault chooses page fault handler according to an entry which was - * read non-atomically. Before making any commitment, on those architectures - * or configurations (e.g. i386 with PAE) which might give a mix of unmatched - * parts, do_swap_page must check under lock before unmapping the pte and - * proceeding (but do_wp_page is only called after already making such a check; - * and do_anonymous_page can safely check later on). - */ -static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, - pte_t *page_table, pte_t orig_pte) -{ - int same = 1; -#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) - if (sizeof(pte_t) > sizeof(unsigned long)) { - spinlock_t *ptl = pte_lockptr(mm, pmd); - spin_lock(ptl); - same = pte_same(*page_table, orig_pte); - spin_unlock(ptl); - } -#endif - pte_unmap(page_table); - return same; -} - static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) { debug_dma_assert_idle(src); @@ -2711,9 +2687,6 @@ int do_swap_page(struct vm_fault *vmf) int exclusive = 0; int ret = 0; - if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) - goto out; - entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) { if (is_migration_entry(entry)) { -- 2.7.4