From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 1223E6B025E for ; Fri, 19 Aug 2016 09:25:15 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id k135so31452750lfb.2 for ; Fri, 19 Aug 2016 06:25:15 -0700 (PDT) Received: from mail-wm0-f65.google.com (mail-wm0-f65.google.com. [74.125.82.65]) by mx.google.com with ESMTPS id ch18si6314638wjb.75.2016.08.19.06.25.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Aug 2016 06:25:13 -0700 (PDT) Received: by mail-wm0-f65.google.com with SMTP id q128so3440222wma.1 for ; Fri, 19 Aug 2016 06:25:13 -0700 (PDT) Date: Fri, 19 Aug 2016 15:25:11 +0200 From: Michal Hocko Subject: Re: [RFC PATCH] kernel/fork: fix CLONE_CHILD_CLEARTID regression in nscd Message-ID: <20160819132511.GH32619@dhcp22.suse.cz> References: <1470039287-14643-1-git-send-email-mhocko@kernel.org> <20160803210804.GA11549@redhat.com> <20160812094113.GE3639@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160812094113.GE3639@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: linux-mm@kvack.org, LKML , Andrew Morton , William Preston , Roland McGrath , Andreas Schwab On Fri 12-08-16 11:41:13, Michal Hocko wrote: > On Wed 03-08-16 23:08:04, Oleg Nesterov wrote: > > sorry for delay, I am travelling till the end of the week. > > Same here... > > > On 08/01, Michal Hocko wrote: [...] > > > We should also check for vfork because > > > this is killable since d68b46fe16ad ("vfork: make it killable"). > > > > Hmm, why? Can't understand... In any case this check doesn't look right, the > > comment says "a killed vfork parent" while tsk->vfork_done != NULL means it > > is a vforked child. > > > > So if we want this change, why we can't simply do > > > > - if (!(tsk->flags & PF_SIGNALED) && > > + if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) && > > > > ? > > This is what I had initially. But then the comment above the check made > me worried that the parent of vforked child might get confused if the > flag is cleared. I might have completely misunderstood the point of the > comment though. So if you believe that vfork_done check is incorrect I > can drop it. It shouldn't have any effect on the nscd usecase AFAIU. So should I drop the vfork check and repost or we do not care about this "regression" and declare nscd broken because it relies on a behavior which is not in fact guaranteed by the kernel? -- Michal Hocko SUSE Labs -- 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