Re: [PATCH 2/2] mm: page allocator: Do not drain per-cpu lists via IPI from page allocator context
From: Mel Gorman <mgorman@suse.de>
Date: 2012-01-12 15:37:12
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On Thu, Jan 12, 2012 at 04:18:12PM +0100, Peter Zijlstra wrote:
On Wed, 2012-01-11 at 10:11 +0000, Mel Gorman wrote:quoted
At least one bug report has been seen on ppc64 against a 3.0 era kernel that looked like a bug receiving interrupts on a CPU being offlined.Got details on that Mel? The preempt_disable() in on_each_cpu() should serialize against the stop_machine() crap in unplug.
I might have added 2 and 2 together and got 5. The stack trace clearly was while sending IPIs in on_each_cpu() and always when under memory pressure and stuck in direct reclaim. This was on !PREEMPT kernels where preempt_disable() is a no-op. That is why I thought get_online_cpu() would be necessary. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>