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From: Michal Hocko <mhocko@kernel.org>
To: Balbir Singh <bsingharora@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: warn about allocations which stall for too long
Date: Mon, 26 Sep 2016 10:13:14 +0200	[thread overview]
Message-ID: <20160926081314.GC27030@dhcp22.suse.cz> (raw)
In-Reply-To: <31729f1f-c0da-29e4-5777-69446daab122@gmail.com>

On Sat 24-09-16 23:19:04, Balbir Singh wrote:
> 
> 
> On 24/09/16 03:34, Dave Hansen wrote:
> > 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.
> 
> An awesome tracepoint and a great place to trigger other tracepoints. With stall timeout
> increasing every time, do we only care about the first instance when we exceeded stall_timeout?
> Do we debug just that instance?

I am not sure I understand you here. The stall_timeout is increased to
see whether the situation is permanent of ephemeral. This is similar to
RCU lockup reports.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID
From: Michal Hocko <mhocko@kernel.org>
To: Balbir Singh <bsingharora@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: warn about allocations which stall for too long
Date: Mon, 26 Sep 2016 10:13:14 +0200	[thread overview]
Message-ID: <20160926081314.GC27030@dhcp22.suse.cz> (raw)
In-Reply-To: <31729f1f-c0da-29e4-5777-69446daab122@gmail.com>

On Sat 24-09-16 23:19:04, Balbir Singh wrote:
> 
> 
> On 24/09/16 03:34, Dave Hansen wrote:
> > 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.
> 
> An awesome tracepoint and a great place to trigger other tracepoints. With stall timeout
> increasing every time, do we only care about the first instance when we exceeded stall_timeout?
> Do we debug just that instance?

I am not sure I understand you here. The stall_timeout is increased to
see whether the situation is permanent of ephemeral. This is similar to
RCU lockup reports.
-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2016-09-26  8:13 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-23  8:15 Michal Hocko
2016-09-23  8:15 ` Michal Hocko
2016-09-23  8:29 ` Hillf Danton
2016-09-23  8:29   ` Hillf Danton
2016-09-23  8:32   ` Michal Hocko
2016-09-23  8:32     ` Michal Hocko
2016-09-23  8:44     ` Hillf Danton
2016-09-23  8:44       ` Hillf Danton
2016-09-23  9:15       ` Michal Hocko
2016-09-23  9:15         ` Michal Hocko
2016-09-23 14:36 ` Tetsuo Handa
2016-09-23 14:36   ` Tetsuo Handa
2016-09-23 15:02   ` Michal Hocko
2016-09-23 15:02     ` Michal Hocko
2016-09-24  3:00     ` Tetsuo Handa
2016-09-24  3:00       ` Tetsuo Handa
2016-09-26  8:17       ` Michal Hocko
2016-09-26  8:17         ` Michal Hocko
2016-09-27 12:57         ` Tetsuo Handa
2016-09-27 12:57           ` Tetsuo Handa
2016-09-29  8:48           ` Michal Hocko
2016-09-29  8:48             ` Michal Hocko
2016-09-23 17:34 ` Dave Hansen
2016-09-23 17:34   ` Dave Hansen
2016-09-24 13:19   ` Balbir Singh
2016-09-24 13:19     ` Balbir Singh
2016-09-26  8:13     ` Michal Hocko [this message]
2016-09-26  8:13       ` Michal Hocko
2016-09-26  8:12   ` Michal Hocko
2016-09-26  8:12     ` Michal Hocko
2016-09-29  8:44 ` [PATCH 0/2] " Michal Hocko
2016-09-29  8:44   ` Michal Hocko
2016-09-29  8:44   ` [PATCH 1/2] mm: consolidate warn_alloc_failed users Michal Hocko
2016-09-29  8:44     ` Michal Hocko
2016-09-29  9:23     ` Vlastimil Babka
2016-09-29  9:23       ` Vlastimil Babka
2016-09-29  8:44   ` [PATCH 2/2] mm: warn about allocations which stall for too long Michal Hocko
2016-09-29  8:44     ` Michal Hocko
2016-09-29  9:02     ` Tetsuo Handa
2016-09-29  9:02       ` Tetsuo Handa
2016-09-29  9:10       ` Michal Hocko
2016-09-29  9:10         ` Michal Hocko

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