From: riel@redhat.com
To: peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
prarit@redhat.com, oleg@redhat.com, sgruszka@redhat.com
Subject: [PATCH -tip 0/2] fix lock inversion in lockless sys_times()
Date: Fri, 12 Sep 2014 09:12:13 -0400 [thread overview]
Message-ID: <1410527535-9814-1-git-send-email-riel@redhat.com> (raw)
The sig->stats_lock nests inside the tasklist_lock and the
sighand->siglock in __exit_signal and wait_task_zombie.
However, both of those locks can be taken from irq context,
which means we need to use the interrupt safe variant of
read_seqbegin_or_lock. This blocks interrupts when the "lock"
branch is taken (seq is odd), preventing the lock inversion.
On the first (lockless) pass through the loop, irqs are not
blocked.
This fixes the lockdep complaints that Stanislaw reported.
next reply other threads:[~2014-09-12 13:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-12 13:12 riel [this message]
2014-09-12 13:12 ` [PATCH -tip 1/2] seqlock: add irqsave variant of read_seqbegin_or_lock riel
2014-09-19 11:44 ` [tip:sched/core] seqlock: Add irqsave variant of read_seqbegin_or_lock() tip-bot for Rik van Riel
2014-09-12 13:12 ` [PATCH -tip 2/2] sched,time: fix lock inversion in thread_group_cputime riel
2014-09-19 11:44 ` [tip:sched/core] sched, time: Fix lock inversion in thread_group_cputime() tip-bot for Rik van Riel
2014-09-14 9:22 ` [PATCH -tip 0/2] fix lock inversion in lockless sys_times() Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1410527535-9814-1-git-send-email-riel@redhat.com \
--to=riel@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=prarit@redhat.com \
--cc=sgruszka@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox