From: Frederic Weisbecker <fweisbec@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Christoph Lameter <cl@linux.com>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 4/5] kmod: Remove unecessary explicit wide CPU affinity setting
Date: Thu, 9 Jul 2015 20:07:16 +0200 [thread overview]
Message-ID: <1436465237-22031-5-git-send-email-fweisbec@gmail.com> (raw)
In-Reply-To: <1436465237-22031-1-git-send-email-fweisbec@gmail.com>
The call_usermodehelper_exec_[a]sync() kernel threads are created by
unbound workqueues precisely because we want them to be affine to all
CPUs, irrespective of any call_usermodehelper() caller with possibly
reduced CPU affinity. So this explicit all-CPUs wide affinity forcing is
useless.
Not only useless it even adds disturbance on isolated CPUs in nohz full
configurations where users set the unbound workqueues low level cpumask
to a reduced set in order to execute non-user-critical work on
housekeeping dedicated CPUs. This reduced affinity is naturally
inherited to usermodehelper kernel threads but the explicit call to
set_cpus_allowed_ptr() breaks that.
So just remove it.
Cc: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
kernel/kmod.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 9ffb24c..d190178 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -221,9 +221,6 @@ static int call_usermodehelper_exec_async(void *data)
flush_signal_handlers(current, 1);
spin_unlock_irq(¤t->sighand->siglock);
- /* We can run anywhere, unlike our parent (unbound workqueue). */
- set_cpus_allowed_ptr(current, cpu_all_mask);
-
/*
* Our parent is the unbound workqueue, which runs with elevated
* scheduling priority. Avoid propagating that into the userspace child.
--
2.1.4
next prev parent reply other threads:[~2015-07-09 18:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-09 18:07 [PATCH 0/5] kmod: Simplifications and cleanups v2 Frederic Weisbecker
2015-07-09 18:07 ` [PATCH 1/5] kmod: Bunch of internal functions renames Frederic Weisbecker
2015-07-09 18:07 ` [PATCH 2/5] kmod: Use system_unbound_wq instead of khelper Frederic Weisbecker
2015-07-09 22:44 ` Oleg Nesterov
2015-07-10 13:47 ` Frederic Weisbecker
2015-07-10 14:20 ` Christoph Lameter
2015-07-10 17:12 ` Frederic Weisbecker
2015-07-10 17:52 ` Christoph Lameter
2015-07-10 18:10 ` Frederic Weisbecker
2015-07-10 19:05 ` Christoph Lameter
2015-07-14 14:04 ` Frederic Weisbecker
2015-07-09 18:07 ` [PATCH 3/5] kmod: Add up-to-date explanations on the purpose of each asynchronous levels Frederic Weisbecker
2015-07-09 18:07 ` Frederic Weisbecker [this message]
2015-07-09 18:07 ` [RFC PATCH 5/5] kmod: Handle UMH_WAIT_PROC from system unbound workqueue Frederic Weisbecker
2015-07-09 22:51 ` Oleg Nesterov
2015-07-10 13:57 ` Frederic Weisbecker
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=1436465237-22031-5-git-send-email-fweisbec@gmail.com \
--to=fweisbec@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=riel@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;
as well as URLs for NNTP newsgroup(s).