From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx121.postini.com [74.125.245.121]) by kanga.kvack.org (Postfix) with SMTP id 835196B0005 for ; Thu, 7 Feb 2013 07:59:14 -0500 (EST) Received: from /spool/local by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 7 Feb 2013 12:57:29 -0000 Received: from d06av10.portsmouth.uk.ibm.com (d06av10.portsmouth.uk.ibm.com [9.149.37.251]) by b06cxnps4075.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r17Cx0iE34865332 for ; Thu, 7 Feb 2013 12:59:00 GMT Received: from d06av10.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av10.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r17BnQqN029404 for ; Thu, 7 Feb 2013 06:49:26 -0500 Date: Thu, 7 Feb 2013 13:59:04 +0100 From: Gerald Schaefer Subject: Re: [PATCH] mm: don't overwrite mm->def_flags in do_mlockall() Message-ID: <20130207135904.0ca7a3d5@thinkpad> In-Reply-To: <20130206125103.61748ed0.akpm@linux-foundation.org> References: <1360165774-55458-1-git-send-email-gerald.schaefer@de.ibm.com> <20130206125103.61748ed0.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vivek Goyal , Hugh Dickins , David Rientjes , Mel Gorman , Martin Schwidefsky , Heiko Carstens , Michel Lespinasse On Wed, 6 Feb 2013 12:51:03 -0800 Andrew Morton wrote: > On Wed, 6 Feb 2013 16:49:34 +0100 > Gerald Schaefer wrote: > > > With commit 8e72033 "thp: make MADV_HUGEPAGE check for > > mm->def_flags" the VM_NOHUGEPAGE flag may be set on s390 in > > mm->def_flags for certain processes, to prevent future thp > > mappings. This would be overwritten by do_mlockall(), which sets it > > back to 0 with an optional VM_LOCKED flag set. > > > > To fix this, instead of overwriting mm->def_flags in do_mlockall(), > > only the VM_LOCKED flag should be set or cleared. > > What are the user-visible effects here? Looking at the 274023da1e8 > changelog, I'm guessing that it might be pretty nasty - kvm breakage? Yes, though at the moment there should be no mlockall()/munlockall() involved with kvm/qemu. So currently no user-visible effects, Vivek found this while reading the do_mlockall() code, but it might be a good idea to add this to stable. Could you add a "Cc: stable@vger.kernel.org # v3.7+"? Thanks, Gerald -- 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