From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f176.google.com (mail-ig0-f176.google.com [209.85.213.176]) by kanga.kvack.org (Postfix) with ESMTP id D80ED6B0069 for ; Mon, 13 Oct 2014 15:07:44 -0400 (EDT) Received: by mail-ig0-f176.google.com with SMTP id hn15so11600908igb.15 for ; Mon, 13 Oct 2014 12:07:44 -0700 (PDT) Received: from smtprelay.hostedemail.com (smtprelay0125.hostedemail.com. [216.40.44.125]) by mx.google.com with ESMTP id h10si1034015igt.36.2014.10.13.12.07.43 for ; Mon, 13 Oct 2014 12:07:44 -0700 (PDT) Message-ID: <1413227261.1287.14.camel@joe-AO725> Subject: Re: [PATCH] mm, debug: mm-introduce-vm_bug_on_mm-fix-fix.patch From: Joe Perches Date: Mon, 13 Oct 2014 12:07:41 -0700 In-Reply-To: <20141013185156.GA1959@redhat.com> References: <5420b8b0.9HdYLyyuTikszzH8%akpm@linux-foundation.org> <1411464279-20158-1-git-send-email-mhocko@suse.cz> <20140923112848.GA10046@dhcp22.suse.cz> <20140923201204.GB4252@redhat.com> <20141013185156.GA1959@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Jones Cc: Linux Kernel , Michal Hocko , Andrew Morton , linux-mm@kvack.org, Sasha Levin On Mon, 2014-10-13 at 14:51 -0400, Dave Jones wrote: > On Tue, Sep 23, 2014 at 04:12:04PM -0400, Dave Jones wrote: > > On Tue, Sep 23, 2014 at 01:28:48PM +0200, Michal Hocko wrote: > > > And there is another one hitting during randconfig. The patch makes my > > > eyes bleed but I don't know about other way without breaking out the > > > thing into separate parts sounds worse because we can mix with other > > > messages then. > > > > how about something along the lines of.. > > > > bufptr = buffer = kmalloc() [] > > It does introduce an allocation though, which may be problematic > > in this situation. Depending how big this gets, perhaps make it static > > instead? > > Now that this landed in Linus tree, I took another stab at it. > Something like this ? (Untested beyond compiling). > > (The diff doesn't really do it justice, it looks a lot easier to read > imo after applying). > > There's still some checkpatch style nits, but this should be a lot > more maintainable assuming it works. > > My one open question is do we care that this isn't reentrant ? > Do we expect parallel calls to dump_mm from multiple cpus ever ? > diff --git a/mm/debug.c b/mm/debug.c [] > @@ -164,74 +164,85 @@ void dump_vma(const struct vm_area_struct *vma) > } > EXPORT_SYMBOL(dump_vma); > > +static char dumpmm_buffer[4096]; Given the maximum single printk is 1024 bytes, a buffer larger than that 1024 bytes is useless. grep LOG_LINE_MAX -- 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