Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932348AbbKLPzx (ORCPT ); Thu, 12 Nov 2015 10:55:53 -0500 Received: from mail-wm0-f53.google.com ([74.125.82.53]:38887 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932070AbbKLPzv (ORCPT ); Thu, 12 Nov 2015 10:55:51 -0500 MIME-Version: 1.0 In-Reply-To: <1447341424-11466-1-git-send-email-jmarchan@redhat.com> References: <1447341424-11466-1-git-send-email-jmarchan@redhat.com> Date: Thu, 12 Nov 2015 18:55:50 +0300 Message-ID: Subject: Re: [PATCH] mm: vmalloc: don't remove inexistent guard hole in remove_vm_area() From: Andrey Ryabinin To: Jerome Marchand Cc: "linux-mm@kvack.org" , LKML , Andrew Morton Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1828 Lines: 50 2015-11-12 18:17 GMT+03:00 Jerome Marchand : > Commit 71394fe50146 ("mm: vmalloc: add flag preventing guard hole > allocation") missed a spot. Currently remove_vm_area() decreases > vm->size to remove the guard hole page, even when it isn't present. > This patch only decreases vm->size when VM_NO_GUARD isn't set. > > Signed-off-by: Jerome Marchand > --- > mm/vmalloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d045634..1388c3d 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1443,7 +1443,8 @@ struct vm_struct *remove_vm_area(const void *addr) > vmap_debug_free_range(va->va_start, va->va_end); > kasan_free_shadow(vm); > free_unmap_vmap_area(va); > - vm->size -= PAGE_SIZE; > + if (!(vm->flags & VM_NO_GUARD)) > + vm->size -= PAGE_SIZE; > I'd fix this in another way. I think that remove_vm_area() shouldn't change vm's size, IMO it doesn't make sense. The only caller who cares about vm's size after removing is __vunmap(): area = remove_vm_area(addr); .... debug_check_no_locks_freed(addr, area->size); debug_check_no_obj_freed(addr, area->size); We already have proper get_vm_area_size() helper which takes VM_NO_GUARD into account. So I think we should use that helper for debug_check_no_*() and just remove 'vm->size -= PAGE_SIZE;' line from remove_vm_area() > return vm; > } > -- > 2.4.3 > -- 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/