on 2010-3-4 11:30, Nick Piggin wrote: > On Wed, Mar 03, 2010 at 06:52:39PM +0800, Miao Xie wrote: >> if MAX_NUMNODES > BITS_PER_LONG, loading/storing task->mems_allowed or mems_allowed in >> task->mempolicy are not atomic operations, and the kernel page allocator gets an empty >> mems_allowed when updating task->mems_allowed or mems_allowed in task->mempolicy. So we >> use a rwlock to protect them to fix this probelm. > > Thanks for working on this. However, rwlocks are pretty nasty to use > when you have short critical sections and hot read-side (they're twice > as heavy as even spinlocks in that case). > > It's being used in the page allocator path, so I would say rwlocks are > almost a showstopper. Wouldn't it be possible to use a seqlock for this? > I will do my best to try to do it. Thanks! Miao -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>