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

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Message-ID: <57E56789.1070205@intel.com>
Date:   Fri, 23 Sep 2016 10:34:01 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org
Cc:     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>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH] mm: warn about allocations which stall for too long

On 09/23/2016 01:15 AM, Michal Hocko wrote:
> +	/* 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),
> +				order, gfp_mask, &gfp_mask);
> +		stall_timeout += 10 * HZ;
> +		dump_stack();
> +	}

This would make an awesome tracepoint.  There's probably still plenty of
value to having it in dmesg, but the configurability of tracepoints is
hard to beat.