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From: Andrew Morton <akpm@linux-foundation.org>
To: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
	m.mizuma@jp.fujitsu.com, mhocko@suse.com,
	catalin.marinas@arm.com, takahiro.akashi@linaro.org,
	gi-oh.kim@profitbricks.com, heiko.carstens@de.ibm.com,
	baiyaowei@cmss.chinamobile.com, richard.weiyang@gmail.com,
	paul.burton@mips.com, miles.chen@mediatek.com, vbabka@suse.cz,
	mgorman@suse.de, hannes@cmpxchg.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [v5 1/2] mm: disable interrupts while initializing deferred pages
Date: Tue, 13 Mar 2018 11:55:49 -0700	[thread overview]
Message-ID: <20180313115549.7badec1c6b85eb5a1cf21eb6@linux-foundation.org> (raw)
In-Reply-To: <20180313160430.hbjnyiazadt3jwa6@xakep.localdomain>

On Tue, 13 Mar 2018 12:04:30 -0400 Pavel Tatashin <pasha.tatashin@oracle.com> wrote:

> > 
> > > --- a/mm/page_alloc.c
> > > +++ b/mm/page_alloc.c
> > > @@ -1506,7 +1506,6 @@ static void __init deferred_free_pages(int nid, int zid, unsigned long pfn,
> > >  		} else if (!(pfn & nr_pgmask)) {
> > >  			deferred_free_range(pfn - nr_free, nr_free);
> > >  			nr_free = 1;
> > > -			cond_resched();
> > >  		} else {
> > >  			nr_free++;
> > 
> > And how can we simply remove these cond_resched()s?  I assume this is
> > being done because interrupts are now disabled?  But those were there
> > for a reason, weren't they?
> 
> We must remove cond_resched() because we can't sleep anymore. They were
> added to fight NMI timeouts, so I will replace them with
> touch_nmi_watchdog() in a follow-up fix.

This makes no sense.  Any code section where we can add cond_resched()
was never subject to NMI timeouts because that code cannot be running with
disabled interrupts.

  reply	other threads:[~2018-03-13 18:55 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-09 22:08 [v5 0/2] initialize pages on demand during boot Pavel Tatashin
2018-03-09 22:08 ` [v5 1/2] mm: disable interrupts while initializing deferred pages Pavel Tatashin
2018-03-12 20:04   ` Andrew Morton
2018-03-13 16:04     ` Pavel Tatashin
2018-03-13 18:55       ` Andrew Morton [this message]
2018-03-13 19:45         ` Pavel Tatashin
2018-03-13 20:11           ` Andrew Morton
2018-03-13 20:43             ` Pavel Tatashin
2018-03-13 21:24               ` Andrew Morton
2018-03-14  0:59                 ` Pavel Tatashin
2018-03-09 22:08 ` [v5 2/2] mm: initialize pages on demand during boot Pavel Tatashin

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