From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 299D61A08E8 for ; Mon, 5 Jan 2015 21:54:27 +1100 (AEDT) From: Mel Gorman To: Andrew Morton Subject: [PATCH 09/10] mm: numa: Add paranoid check around pte_protnone_numa Date: Mon, 5 Jan 2015 10:54:10 +0000 Message-Id: <1420455251-13644-10-git-send-email-mgorman@suse.de> In-Reply-To: <1420455251-13644-1-git-send-email-mgorman@suse.de> References: <1420455251-13644-1-git-send-email-mgorman@suse.de> Cc: Rik van Riel , Hugh Dickins , Linux Kernel , Linux-MM , Ingo Molnar , Aneesh Kumar , Sasha Levin , LinuxPPC-dev , Kirill Shutemov , Mel Gorman List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are complete. Treating a real PROT_NONE PTE as a NUMA hinting fault is going to result in strangeness so add a check for it. BUG_ON looks like overkill but if this is hit then it's a serious bug that could result in corruption so do not even try recovering. It would have been more comprehensive to check VMA flags in pte_protnone_numa but it would have made the API ugly just for a debugging check. Signed-off-by: Mel Gorman --- mm/huge_memory.c | 3 +++ mm/memory.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index ad2a3ee..8546654 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1273,6 +1273,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, bool migrated = false; int flags = 0; + /* A PROT_NONE fault should not end up here */ + BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); + ptl = pmd_lock(mm, pmdp); if (unlikely(!pmd_same(pmd, *pmdp))) goto out_unlock; diff --git a/mm/memory.c b/mm/memory.c index 3c50046..9df2d09 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3108,6 +3108,9 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, bool migrated = false; int flags = 0; + /* A PROT_NONE fault should not end up here */ + BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); + /* * The "pte" at this point cannot be used safely without * validation through pte_unmap_same(). It's of NUMA type but -- 2.1.2