From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx125.postini.com [74.125.245.125]) by kanga.kvack.org (Postfix) with SMTP id 72C0F6B004D for ; Thu, 1 Nov 2012 19:48:46 -0400 (EDT) Received: by mail-ie0-f169.google.com with SMTP id 10so5364784ied.14 for ; Thu, 01 Nov 2012 16:48:45 -0700 (PDT) Date: Thu, 1 Nov 2012 16:48:41 -0700 (PDT) From: Hugh Dickins Subject: Re: shmem_getpage_gfp VM_BUG_ON triggered. [3.7rc2] In-Reply-To: <20121101232030.GA25519@redhat.com> Message-ID: References: <20121025023738.GA27001@redhat.com> <20121101191052.GA5884@redhat.com> <20121101232030.GA25519@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Jones , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, 1 Nov 2012, Dave Jones wrote: > On Thu, Nov 01, 2012 at 04:03:40PM -0700, Hugh Dickins wrote: > > > > Except... earlier in the thread you explained how you hacked > > #define VM_BUG_ON(cond) WARN_ON(cond) > > to get this to come out as a warning instead of a bug, > > and now it looks as if "a user" has here done the same. > > > > Which is very much a user's right, of course; but does > > make me wonder whether that user might actually be davej ;) > > indirectly. I made the same change in the Fedora kernel a while ago > to test a hypothesis that we weren't getting any VM_BUG_ON reports. Fedora turns on CONFIG_DEBUG_VM? All mm developers should thank you for the wider testing exposure; but I'm not so sure that Fedora users should thank you for turning it on - really it's for mm developers to wrap around !assertions or more expensive checks (e.g. checking calls) in their development. Or did I read a few months ago that some change had been made to such definitions, and VM_BUG_ON(contents) are evaluated even when the config option is off? I do hope I'm mistaken on that. Hugh -- 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