Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760679AbXEOSKc (ORCPT ); Tue, 15 May 2007 14:10:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755947AbXEOSKY (ORCPT ); Tue, 15 May 2007 14:10:24 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:48935 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754948AbXEOSKX (ORCPT ); Tue, 15 May 2007 14:10:23 -0400 Date: Tue, 15 May 2007 11:10:22 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andrew Morton cc: Badari Pulavarty , netdev@vger.kernel.org, lkml Subject: Re: select(0, ..) is valid ? In-Reply-To: <20070515104453.f901e91f.akpm@linux-foundation.org> Message-ID: References: <1179250159.2836.117.camel@dyn9047017100.beaverton.ibm.com> <20070515104453.f901e91f.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1323 Lines: 40 On Tue, 15 May 2007, Andrew Morton wrote: > I _think_ we can just do > > --- a/fs/compat.c~a > +++ a/fs/compat.c > @@ -1566,9 +1566,13 @@ int compat_core_sys_select(int n, compat > */ > ret = -ENOMEM; > size = FDS_BYTES(n); > - bits = kmalloc(6 * size, GFP_KERNEL); > - if (!bits) > - goto out_nofds; > + if (likely(size)) { > + bits = kmalloc(6 * size, GFP_KERNEL); > + if (!bits) > + goto out_nofds; > + } else { > + bits = NULL; > + } > fds.in = (unsigned long *) bits; > fds.out = (unsigned long *) (bits + size); > fds.ex = (unsigned long *) (bits + 2*size); > _ > > I mean, if that oopses then I'd be very interested in finding out why. > > But I'm starting to suspect that it would be better to permit kmalloc(0) in > slub. It depends on how many more of these things need fixing. > > otoh, a kmalloc(0) could be a sign of some buggy/inefficient/weird code, so > there's some value in forcing us to go look at all the callsites. Hmmm... We could have kmalloc(0) return a pointer to the zero page? That would catch any writers? - 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/