Hello, Vladmir. On Fri, Aug 28, 2015 at 11:45:54PM +0300, Vladimir Davydov wrote: > Actually, memory.high by itself *is* the protection against GFP_NOWAIT > allocations, similarly to zone watermarks. W/o it we would have no other > choice but fail a GFP_NOWAIT allocation on hitting memory.max. One > should just set it so that > > memory.max - memory.high > [max sum size of !__GFP_WAIT allocations > that can normally occur in a row] While this would be true in many cases, I don't think this is the intention of the two knobs and the space between high and max can be filled up by anything which can't be reclaimed - e.g. too many dirty / writeback pages on a slow device or memlocked pages. If it were really the buffer for GFP_NOWAIT, there's no reason to even make it a separate knob and we *may* change how over-high reclaim behaves in the future, so let's please not dig ourselves into something too specific. > That being said, currently I don't see any point in making memory.high > !__GFP_WAIT-safe. Yeah, as long as the blow up can't be triggered consistently, it should be fine. Thanks. -- tejun -- 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>