linux-kernel - Re: [RFC PATCH v4 01/13] ktask: add documentation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20181107202145.xvaq3pmqbzyekfan@ca-dmjordan1.us.oracle.com>
Date:   Wed, 7 Nov 2018 12:21:45 -0800
From:   Daniel Jordan <daniel.m.jordan@...cle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Jason Gunthorpe <jgg@...lanox.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "aarcange@...hat.com" <aarcange@...hat.com>,
        "aaron.lu@...el.com" <aaron.lu@...el.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "bsd@...hat.com" <bsd@...hat.com>,
        "darrick.wong@...cle.com" <darrick.wong@...cle.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "jwadams@...gle.com" <jwadams@...gle.com>,
        "jiangshanlai@...il.com" <jiangshanlai@...il.com>,
        "mhocko@...nel.org" <mhocko@...nel.org>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "Pavel.Tatashin@...rosoft.com" <Pavel.Tatashin@...rosoft.com>,
        "prasad.singamsetty@...cle.com" <prasad.singamsetty@...cle.com>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "steven.sistare@...cle.com" <steven.sistare@...cle.com>,
        "tim.c.chen@...el.com" <tim.c.chen@...el.com>,
        "tj@...nel.org" <tj@...nel.org>, "vbabka@...e.cz" <vbabka@...e.cz>
Subject: Re: [RFC PATCH v4 01/13] ktask: add documentation

On Wed, Nov 07, 2018 at 11:27:52AM +0100, Peter Zijlstra wrote:
> On Tue, Nov 06, 2018 at 08:51:54PM +0000, Jason Gunthorpe wrote:
> > On Tue, Nov 06, 2018 at 12:34:11PM -0800, Daniel Jordan wrote:
> > 
> > > > What isn't clear is if this calling thread is waiting or not. Only do
> > > > this inheritance trick if it is actually waiting on the work. If it is
> > > > not, nobody cares.
> > > 
> > > The calling thread waits.  Even if it didn't though, the inheritance trick
> > > would still be desirable for timely completion of the job.
> > 
> > Can you make lockdep aware that this is synchronous?
> > 
> > ie if I do
> > 
> >   mutex_lock()
> >   ktask_run()
> >   mutex_lock()
> > 
> > Can lockdep know that all the workers are running under that lock?
> > 
> > I'm thinking particularly about rtnl_lock as a possible case, but
> > there could also make some sense to hold the read side of the mm_sem
> > or similar like the above.
> 
> Yes, the normal trick is adding a fake lock to ktask_run and holding
> that over the actual job. See lock_map* in flush_workqueue() vs
> process_one_work().

I'll add that for the next version.