From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Subject: Re: [PATCH 2/2] mm: page allocator: Do not drain per-cpu lists via IPI from page allocator context Date: Thu, 12 Jan 2012 15:37:12 +0000 Message-ID: <20120112153712.GL4118@suse.de> References: <1326276668-19932-1-git-send-email-mgorman@suse.de> <1326276668-19932-3-git-send-email-mgorman@suse.de> <1326381492.2442.188.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Cc: Linux-MM , Linux-FSDevel , LKML , Andrew Morton , "Srivatsa S. Bhat" , Russell King - ARM Linux , Gilad Ben-Yossef , "Paul E. McKenney" , Miklos Szeredi , "Eric W. Biederman" , Greg KH , Gong Chen To: Peter Zijlstra Return-path: Content-Disposition: inline In-Reply-To: <1326381492.2442.188.camel@twins> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org 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: > > 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: email@kvack.org