This is my attempt to fix the recent report based on LTP cpuset stress test [1]. Patches are based on 4.9 as that was the initial reported version, but later it was reported that this problem exists since 4.7. We will probably want to go to stable with this, as triggering OOMs is not nice. That's why the patches try to be not too intrusive. Longer-term we might try to think how to fix the cpuset mess in a better and less error prone way. I was for example very surprised to learn, that cpuset updates change not only task->mems_allowed, but also nodemask of mempolicies. Until now I expected the parameter to alloc_pages_nodemask() to be stable. I wonder why do we then treat cpusets specially in get_page_from_freelist() and distinguish HARDWALL etc, when there's unconditional intersection between mempolicy and cpuset. I would expect the nodemask adjustment for saving overhead in g_p_f(), but that clearly doesn't happen in the current form. So we have both crazy complexity and overhead, AFAICS. [1] https://lkml.kernel.org/r/CAFpQJXUq-JuEP=QPidy4p_=FN0rkH5Z-kfB4qBvsf6jMS87Edg@xxxxxxxxxxxxxx Vlastimil Babka (4): mm, page_alloc: fix check for NULL preferred_zone mm, page_alloc: fix fast-path race with cpuset update or removal mm, page_alloc: move cpuset seqcount checking to slowpath mm, page_alloc: fix premature OOM when racing with cpuset mems update mm/page_alloc.c | 58 ++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 37 insertions(+), 21 deletions(-) -- 2.11.0 -- 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>
