Michal Hocko wrote: > + target -= (stall_backoff * target + MAX_STALL_BACKOFF - 1) / MAX_STALL_BACKOFF; target -= DIV_ROUND_UP(stall_backoff * target, MAX_STALL_BACKOFF); Michal Hocko wrote: > This alone wouldn't be sufficient, though, because the writeback might > get stuck and reclaimable pages might be pinned for a really long time > or even depend on the current allocation context. Is this a dependency which I worried at http://lkml.kernel.org/r/201510262044.BAI43236.FOMSFFOtOVLJQH@xxxxxxxxxxxxxxxxxxx ? > Therefore there is a > feedback mechanism implemented which reduces the reclaim target after > each reclaim round without any progress. If yes, this feedback mechanism will help avoiding infinite wait loop. > This means that we should > eventually converge to only NR_FREE_PAGES as the target and fail on the > wmark check and proceed to OOM. What if all in-flight allocation requests are !__GFP_NOFAIL && !__GFP_FS ? (In other words, either "no __GFP_FS allocations are in-flight" or "all __GFP_FS allocations are in-flight but are either waiting for completion of operations which depend on !__GFP_FS allocations with a lock held or waiting for that lock to be released".) Don't we need to call out_of_memory() even though !__GFP_FS allocations? > The backoff is simple and linear with > 1/16 of the reclaimable pages for each round without any progress. We > are optimistic and reset counter for successful reclaim rounds. -- 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>