On Tue, Dec 04, 2012 at 06:37:41AM -0800, Michel Lespinasse wrote: > On Mon, Dec 3, 2012 at 6:17 AM, Mel Gorman <mgorman@xxxxxxx> wrote: > > On Sat, Dec 01, 2012 at 09:15:38PM +0100, Ingo Molnar wrote: > >> @@ -732,7 +732,7 @@ static int page_referenced_anon(struct p > >> struct anon_vma_chain *avc; > >> int referenced = 0; > >> > >> - anon_vma = page_lock_anon_vma(page); > >> + anon_vma = page_lock_anon_vma_read(page); > >> if (!anon_vma) > >> return referenced; > > > > This is a slightly trickier one as this path is called from reclaim. It does > > open the possibility that reclaim can stall something like a parallel fork > > or anything that requires the anon_vma rwsem for a period of time. I very > > severely doubt it'll really be a problem but keep an eye out for bug reports > > related to delayed mmap/fork/anything_needing_write_lock during page reclaim. > > I don't see why this would be a problem - rwsem does implement > reader/writer fairness, so having some sites do a read lock instead of > a write lock shouldn't cause the write lock sites to starve. Is this > what you were worried about ? > Yes. I did not expect they would be starved forever, just delayed longer than they might have been before. I would be very surprised if there is anything other than a synthetic case that will really care but I've been "very surprised" before :) -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>