On Sat 24-09-16 23:19:04, Balbir Singh wrote:

On 24/09/16 03:34, Dave Hansen wrote:

quoted

On 09/23/2016 01:15 AM, Michal Hocko wrote:

quoted

+	/* 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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