linux-kernel - gFrom 9667d5ddbb1dc230653e5f8cedb778e9c562d46c Mon Sep 17 00:00:00 2001

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-next>] [day] [month] [year] [list]

Message-Id: <20201024225716.2854163-1-xii@google.com>
Date:   Sat, 24 Oct 2020 15:57:15 -0700
From:   Xi Wang <xii@...gle.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Don <joshdon@...gle.com>, linux-kernel@...r.kernel.org
Subject: gFrom 9667d5ddbb1dc230653e5f8cedb778e9c562d46c Mon Sep 17 00:00:00 2001

Instead of periodically resetting watchdogs from thread context,
this patch simply forces resched and checks rq->sched_count.
Watchdog is reset if the sched count increases. If the same thread
is picked by pick_next_task during resched, there is no context
switch.

With the new method we lose coverage on: a migration/n thread
actually gets picked and we actually context switch to the
migration/n thread. These steps are unlikely to silently fail.
The change would provide nearly the same level of protection with
less latency / jitter.

v3:
 - Removed the old method and boot option
 - Still need to check resched

v2:
 - Use sched_count instead of having sched calling into watchdog code
 - Remove the sysctl and add a boot option, which can be removed later
 - Changed the subject line

Xi Wang (1):
  sched: watchdog: Touch kernel watchdog with sched count

 include/linux/sched.h |  4 ++++
 kernel/sched/core.c   | 23 +++++++++++++++++++--
 kernel/sched/sched.h  |  6 +++++-
 kernel/watchdog.c     | 47 +++++++++++++------------------------------
 4 files changed, 44 insertions(+), 36 deletions(-)

-- 
2.29.0.rc2.309.g374f81d7ae-goog