Messages in this thread | | | Subject | Re: [PATCH] mm, lockdep: annotate reclaim context to zone reclaim too | From | Peter Zijlstra <> | Date | Sat, 02 Jan 2010 11:46:06 +0100 |
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On Sat, 2010-01-02 at 14:21 +0900, KOSAKI Motohiro wrote: > 2010/1/2 Peter Zijlstra <peterz@infradead.org>: > > On Fri, 2010-01-01 at 18:45 +0900, KOSAKI Motohiro wrote: > >> Commit cf40bd16fd (lockdep: annotate reclaim context) introduced reclaim > >> context annotation. But it didn't annotate zone reclaim. This patch do it. > > > > And yet you didn't CC anyone involved in that patch, nor explain why you > > think it necessary, massive FAIL. > > > > The lockdep annotations cover all of kswapd() and direct reclaim through > > __alloc_pages_direct_reclaim(). So why would you need an explicit > > annotation in __zone_reclaim()? > > Thanks CCing. The point is zone-reclaim doesn't use > __alloc_pages_direct_reclaim. > current call graph is > > __alloc_pages_nodemask > get_page_from_freelist > zone_reclaim() > __alloc_pages_slowpath > __alloc_pages_direct_reclaim > try_to_free_pages > > Actually, if zone_reclaim_mode=1, VM never call > __alloc_pages_direct_reclaim in usual VM pressure. > Thus I think zone-reclaim should be annotated explicitly too. > I know almost user don't use zone reclaim mode. but explicit > annotation doesn't have any demerit, I think.
Just be aware that the annotation isn't recursive, I'd have to trace all calls to __zone_reclaim, but if kswapd were ever to call it you'd just wrecked things by getting lockdep_clear_current_reclaim_state() called.
So just make sure you don't shorten the existing notations by adding it here. Other than that it seems ok.
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