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  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]
Date:   Thu, 9 Nov 2017 20:03:30 +0900
From:   Tetsuo Handa <>
Subject: Re: [PATCH v4] printk: Add console owner and waiter logic to loadbalance console writes

Michal Hocko wrote:
> On Thu 09-11-17 19:22:58, Tetsuo Handa wrote:
> > Michal Hocko wrote:
> > > Hi,
> > > assuming that this passes warn stall torturing by Tetsuo, do you think
> > > we can drop
> > > from the mmotm tree?
> > 
> > I don't think so.
> > 
> > The rule that "do not try to printk() faster than the kernel can write to
> > consoles" will remain no matter how printk() changes. Unless asynchronous
> > approach like is used, I think we can't
> > obtain useful information.
> Does that mean that the patch doesn't pass your test?

Test is irrelevant. See the changelog.

  Synchronous approach is prone to unexpected results (e.g. too late [1], too
  frequent [2], overlooked [3]). As far as I know, warn_alloc() never helped
  with providing information other than "something is going wrong".
  I want to consider asynchronous approach which can obtain information
  during stalls with possibly relevant threads (e.g. the owner of oom_lock
  and kswapd-like threads) and serve as a trigger for actions (e.g. turn
  on/off tracepoints, ask libvirt daemon to take a memory dump of stalling
  KVM guest for diagnostic purpose).

  [3] commit db73ee0d46379922 ("mm, vmscan: do not loop on too_many_isolated for ever")

Powered by blists - more mailing lists