From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 16 Nov 2016 01:28:19 +0300 From: "Kirill A. Shutemov" To: Jan Kara Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, Andrew Morton , Ross Zwisler , "Kirill A. Shutemov" Subject: Re: [PATCH 11/21] mm: Remove unnecessary vma->vm_ops check Message-ID: <20161115222819.GK23021@node> References: <1478233517-3571-1-git-send-email-jack@suse.cz> <1478233517-3571-12-git-send-email-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1478233517-3571-12-git-send-email-jack@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: On Fri, Nov 04, 2016 at 05:25:07AM +0100, Jan Kara wrote: > We don't check whether vma->vm_ops is NULL in do_shared_fault() so > there's hardly any point in checking it in wp_page_shared() or > wp_pfn_shared() which get called only for shared file mappings as well. > > Signed-off-by: Jan Kara Well, I'm not sure about this. do_shared_fault() doesn't have the check since we checked it upper by stack: see vma_is_anonymous() in handle_pte_fault(). In principal, it should be fine. But random crappy driver has potential to blow it up. > --- > mm/memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 7be96a43d5ac..26b2858e6a12 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2275,7 +2275,7 @@ static int wp_pfn_shared(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > > - if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { > + if (vma->vm_ops->pfn_mkwrite) { > int ret; > > pte_unmap_unlock(vmf->pte, vmf->ptl); > @@ -2305,7 +2305,7 @@ static int wp_page_shared(struct vm_fault *vmf, struct page *old_page) > > get_page(old_page); > > - if (vma->vm_ops && vma->vm_ops->page_mkwrite) { > + if (vma->vm_ops->page_mkwrite) { > int tmp; > > pte_unmap_unlock(vmf->pte, vmf->ptl); > -- > 2.6.6 > > -- > 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 -- Kirill A. Shutemov -- 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