From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:33690) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TTW9c-00085p-8J for qemu-devel@nongnu.org; Wed, 31 Oct 2012 07:08:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TTW9S-0007LS-9S for qemu-devel@nongnu.org; Wed, 31 Oct 2012 07:08:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53178) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TTW9S-0007Kw-1O for qemu-devel@nongnu.org; Wed, 31 Oct 2012 07:08:02 -0400 Message-ID: <509106A0.7020400@redhat.com> Date: Wed, 31 Oct 2012 13:08:16 +0200 From: Orit Wasserman MIME-Version: 1.0 References: <1351654988-13165-1-git-send-email-david@gibson.dropbear.id.au> In-Reply-To: <1351654988-13165-1-git-send-email-david@gibson.dropbear.id.au> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] Fix off-by-1 error in RAM migration code List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org On 10/31/2012 05:43 AM, David Gibson wrote: > The code for migrating (or savevm-ing) memory pages starts off by creating > a dirty bitmap and filling it with 1s. Except, actually, because bit > addresses are 0-based it fills every bit except bit 0 with 1s and puts an > extra 1 beyond the end of the bitmap, potentially corrupting unrelated > memory. Oops. This patch fixes it. > > Signed-off-by: David Gibson > --- > arch_init.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch_init.c b/arch_init.c > index e6effe8..b75a4c5 100644 > --- a/arch_init.c > +++ b/arch_init.c > @@ -568,7 +568,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque) > int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS; > > migration_bitmap = bitmap_new(ram_pages); > - bitmap_set(migration_bitmap, 1, ram_pages); > + bitmap_set(migration_bitmap, 0, ram_pages); > migration_dirty_pages = ram_pages; > > bytes_transferred = 0; > You are correct, good catch. Reviewed-by: Orit Wasserman