From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f175.google.com (mail-lb0-f175.google.com [209.85.217.175]) by kanga.kvack.org (Postfix) with ESMTP id 03FF46B007E for ; Sat, 2 Apr 2016 11:37:51 -0400 (EDT) Received: by mail-lb0-f175.google.com with SMTP id bc4so100866057lbc.2 for ; Sat, 02 Apr 2016 08:37:50 -0700 (PDT) Received: from mail-lb0-x236.google.com (mail-lb0-x236.google.com. [2a00:1450:4010:c04::236]) by mx.google.com with ESMTPS id f184si11005354lfg.145.2016.04.02.08.37.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 02 Apr 2016 08:37:49 -0700 (PDT) Received: by mail-lb0-x236.google.com with SMTP id qe11so100809977lbc.3 for ; Sat, 02 Apr 2016 08:37:49 -0700 (PDT) Subject: [PATCH] mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check From: Konstantin Khlebnikov Date: Sat, 02 Apr 2016 18:37:44 +0300 Message-ID: <145961146490.28194.16019687861681349309.stgit@zurg> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, Andrew Morton Cc: Dmitry Vyukov , Andrea Arcangeli , linux-kernel@vger.kernel.org, stable Khugepaged detects own VMAs by checking vm_file and vm_ops but this way it cannot distinguish private /dev/zero mappings from other special mappings like /dev/hpet which has no vm_ops and popultes PTEs in mmap. This fixes false-positive VM_BUG_ON and prevents installing THP where they are not expected. Signed-off-by: Konstantin Khlebnikov Reported-by: Dmitry Vyukov Link: http://lkml.kernel.org/r/CACT4Y+ZmuZMV5CjSFOeXviwQdABAgT7T+StKfTqan9YDtgEi5g@mail.gmail.com Fixes: 78f11a255749 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups") Cc: stable --- mm/huge_memory.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 86f9f8b82f8e..93de199ba0f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1960,10 +1960,9 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma, * page fault if needed. */ return 0; - if (vma->vm_ops) + if (vma->vm_ops || (vm_flags & VM_NO_THP)) /* khugepaged not yet working on file or special mappings */ return 0; - VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) @@ -2352,8 +2351,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) return false; if (is_vma_temporary_stack(vma)) return false; - VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); - return true; + return !(vma->vm_flags & VM_NO_THP); } static void collapse_huge_page(struct mm_struct *mm, -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org