On 6/18/2012 12:47 PM, Ying Han wrote: > Currently, do_try_to_free_pages() can enter livelock. Because of, > now vmscan has two conflicted policies. > > 1) kswapd sleep when it couldn't reclaim any page even though > reach priority 0. This is because to avoid kswapd() infinite > loop. That said, kswapd assume direct reclaim makes enough > free pages either regular page reclaim or oom-killer. > This logic makes kswapd -> direct-reclaim dependency. > 2) direct reclaim continue to reclaim without oom-killer until > kswapd turn on zone->all_unreclaimble. This is because > to avoid too early oom-kill. > This logic makes direct-reclaim -> kswapd dependency. > > In worst case, direct-reclaim may continue to page reclaim forever > when kswapd is slept and any other thread don't wakeup kswapd. > > We can't turn on zone->all_unreclaimable because this is racy. > direct reclaim path don't take any lock. Thus this patch removes > zone->all_unreclaimable field completely and recalculates every > time. > > Note: we can't take the idea that direct-reclaim see zone->pages_scanned > directly and kswapd continue to use zone->all_unreclaimable. Because, > it is racy. commit 929bea7c71 (vmscan: all_unreclaimable() use > zone->all_unreclaimable as a name) describes the detail. > > Reported-by: Aaditya Kumar <aaditya.kumar.30@xxxxxxxxx> > Reported-by: Ying Han <yinghan@xxxxxxxxxx> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Acked-by: Rik van Riel <riel@xxxxxxxxxx> Please drop this. I've got some review comment about this patch and i need respin. but thank you for paying attention this. -- 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>