From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id 5791A6B0012 for ; Fri, 27 May 2011 18:10:29 -0400 (EDT) Date: Fri, 27 May 2011 15:09:56 -0700 From: Andrew Morton Subject: Re: [PATCH] mm: nommu: fix remap_pfn_range() Message-Id: <20110527150956.e55577c5.akpm@linux-foundation.org> In-Reply-To: <1306468203-8683-1-git-send-email-lliubbo@gmail.com> References: <1306468203-8683-1-git-send-email-lliubbo@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Bob Liu Cc: gerg@snapgear.com, dhowells@redhat.com, lethal@linux-sh.org, geert@linux-m68k.org, vapier@gentoo.org, linux-mm@kvack.org On Fri, 27 May 2011 11:50:03 +0800 Bob Liu wrote: > remap_pfn_range() does not update vma->end on no mmu arch which will > cause munmap() fail because it can't match the vma. > > eg. fb_mmap() in fbmem.c will call io_remap_pfn_range() which is > remap_pfn_range() on nommu arch, if an address is not page aligned vma->start > will be changed in remap_pfn_range(), but neither size nor vma->end will be > updated. Then munmap(start, len) can't find the vma to free, because it need to > compare (start + len) with vma->end. > > Signed-off-by: Bob Liu > --- > mm/nommu.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/mm/nommu.c b/mm/nommu.c > index 1fd0c51..829848a 100644 > --- a/mm/nommu.c > +++ b/mm/nommu.c > @@ -1817,6 +1817,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, > unsigned long to, unsigned long size, pgprot_t prot) > { > vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; > + vma->vm_end = vma->vm_start + size; > return 0; > } > EXPORT_SYMBOL(remap_pfn_range); hm. The MMU version of remap_pfn_range() doesn't do this. Seems that it just leaves the omitted parts of the vma unmapped. Obviously nommu can't do that, but the divergence is always a concern. Thsi implementation could lead to overlapping vmas. Should we be checking that it fits? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org