From: Marcelo Tosatti <mtosatti@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users@vger.kernel.org,
Juri Lelli <juri.lelli@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [patch 2/2] mm: page_alloc: drain pages remotely
Date: Tue, 16 Jun 2020 14:04:25 -0300 [thread overview]
Message-ID: <20200616170425.GA324900@fuller.cnet> (raw)
In-Reply-To: <20200616163248.z5bdrx7gj2sf7d3m@linutronix.de>
On Tue, Jun 16, 2020 at 06:32:48PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-06-16 13:11:51 [-0300], Marcelo Tosatti wrote:
> > Remote draining of pages was removed from 5.6-rt.
> >
> > Unfortunately its necessary for use-cases which have a busy spinning
> > SCHED_FIFO thread on isolated CPU:
> >
> > [ 7475.821066] INFO: task ld:274531 blocked for more than 600 seconds.
> > [ 7475.822157] Not tainted 4.18.0-208.rt5.20.el8.x86_64 #1
> > [ 7475.823094] echo 0 /proc/sys/kernel/hung_task_timeout_secs disables this message.
> > [ 7475.824392] ld D 0 274531 274530 0x00084080
> > [ 7475.825307] Call Trace:
> > [ 7475.825761] __schedule+0x342/0x850
> > [ 7475.826377] schedule+0x39/0xd0
> > [ 7475.826923] schedule_timeout+0x20e/0x410
> > [ 7475.827610] ? __schedule+0x34a/0x850
> > [ 7475.828247] ? ___preempt_schedule+0x16/0x18
> > [ 7475.828953] wait_for_completion+0x85/0xe0
> > [ 7475.829653] flush_work+0x11a/0x1c0
> > [ 7475.830313] ? flush_workqueue_prep_pwqs+0x130/0x130
> > [ 7475.831148] drain_all_pages+0x140/0x190
> > [ 7475.831803] __alloc_pages_slowpath+0x3f8/0xe20
> > [ 7475.832571] ? mem_cgroup_commit_charge+0xcb/0x510
> > [ 7475.833371] __alloc_pages_nodemask+0x1ca/0x2b0
> > [ 7475.834134] pagecache_get_page+0xb5/0x2d0
> > [ 7475.834814] ? account_page_dirtied+0x11a/0x220
> > [ 7475.835579] grab_cache_page_write_begin+0x1f/0x40
> > [ 7475.836379] iomap_write_begin.constprop.44+0x1c1/0x370
> > [ 7475.837241] ? iomap_write_end+0x91/0x290
> > [ 7475.837911] iomap_write_actor+0x92/0x170
> > ...
> >
> > So enable remote draining again.
>
> Is upstream affected by this? And if not, why not?
It is affected. The workqueue thread for a given CPU is SCHED_OTHER, which can't
interrupt a SCHED_FIFO task which does not sleep.
next prev parent reply other threads:[~2020-06-16 17:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 16:11 [patch 0/2] re-enable remote per-cpu-pages draining Marcelo Tosatti
2020-06-16 16:11 ` [patch 1/2] rt: add local_lock_on and local_lock_irqsave_on to locallock.h Marcelo Tosatti
2020-06-16 16:11 ` [patch 2/2] mm: page_alloc: drain pages remotely Marcelo Tosatti
2020-06-16 16:32 ` Sebastian Andrzej Siewior
2020-06-16 16:55 ` Marcelo Tosatti
2020-06-17 7:42 ` Sebastian Andrzej Siewior
2020-06-17 10:11 ` Marcelo Tosatti
2020-06-17 12:01 ` Sebastian Andrzej Siewior
2020-06-16 17:04 ` Marcelo Tosatti [this message]
2020-06-17 7:46 ` Sebastian Andrzej Siewior
2020-06-17 10:12 ` Marcelo Tosatti
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=20200616170425.GA324900@fuller.cnet \
--to=mtosatti@redhat.com \
--cc=bigeasy@linutronix.de \
--cc=frederic@kernel.org \
--cc=juri.lelli@redhat.com \
--cc=linux-rt-users@vger.kernel.org \
--cc=tglx@linutronix.de \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.