linux-kernel - Re: [PATCH] mm: warn about allocations which stall for too long

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Message-ID: <20160923091555.GH4478@dhcp22.suse.cz>
Date:   Fri, 23 Sep 2016 11:15:55 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Hillf Danton <hillf.zj@...baba-inc.com>
Cc:     linux-mm@...ck.org, 'Andrew Morton' <akpm@...ux-foundation.org>,
        'Johannes Weiner' <hannes@...xchg.org>,
        'Mel Gorman' <mgorman@...e.de>,
        'Tetsuo Handa' <penguin-kernel@...ove.SAKURA.ne.jp>,
        'LKML' <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: warn about allocations which stall for too long

On Fri 23-09-16 16:44:26, Hillf Danton wrote:
> On Friday, September 23, 2016 4:32 PM, Michal Hocko wrote
> > On Fri 23-09-16 16:29:36, Hillf Danton wrote:
> > [...]
> > > > @@ -3659,6 +3661,15 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> > > >  	else
> > > >  		no_progress_loops++;
> > > >
> > > > +	/* Make sure we know about allocations which stall for too long */
> > > > +	if (!(gfp_mask & __GFP_NOWARN) && time_after(jiffies, alloc_start + stall_timeout)) {
> > > > +		pr_warn("%s: page alloction stalls for %ums: order:%u mode:%#x(%pGg)\n",
> > > > +				current->comm, jiffies_to_msecs(jiffies-alloc_start),
> > >
> > > Better if pid is also printed.
> > 
> > I've tried to be consistent with warn_alloc_failed and that doesn't
> > print pid either. Maybe both of them should. Dunno
> > 
> With pid imho we can distinguish two tasks with same name in a simpler way. 

I've just checked dump_stack and dump_stack_print_info provides that
information already.
-- 
Michal Hocko
SUSE Labs