linux-kernel - Re: [PATCH][RFC v2] PM / Hibernate: Disable wathdog when creating snapshot

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Date:   Wed, 16 Aug 2017 22:33:02 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][RFC v2] PM / Hibernate: Disable wathdog when creating
 snapshot

On Wed, Aug 16, 2017 at 02:33:59PM +0200, Michal Hocko wrote:
> On Wed 16-08-17 12:53:38, Chen Yu wrote:
> [...]
> > @@ -2537,10 +2538,15 @@ void mark_free_pages(struct zone *zone)
> >  	unsigned long flags;
> >  	unsigned int order, t;
> >  	struct page *page;
> > +	bool wd_suspended;
> >  
> >  	if (zone_is_empty(zone))
> >  		return;
> >  
> > +	wd_suspended = lockup_detector_suspend() ? false : true;
> > +	if (!wd_suspended)
> > +		pr_warn_once("Failed to disable lockup detector during hibernation.\n");
> > +
> >  	spin_lock_irqsave(&zone->lock, flags);
> >  
> >  	max_zone_pfn = zone_end_pfn(zone);
> 
> I am not maintainer of this code so I am not very familiar with the full
> context of this function but lockup_detector_suspend is just too heavy
> for the purpose you are trying to achive. Really why don't you just
> poke the watchdog every N pages?
OK, I'll send another version.
Thanks,
	Yu
> -- 
> Michal Hocko
> SUSE Labs