on 2010-2-23 6:00, David Rientjes wrote: > On Mon, 22 Feb 2010, Nick Piggin wrote: > >> If you have a concurrent reader without any synchronisation, then what >> stops it from loading a word of the mask before stores to add the new >> nodes and then loading another word of the mask after the stores to >> remove the old nodes? (which can give an empty mask). >> > > Currently nothing, so we'll need a variant for configurations where the > size of nodemask_t is larger than we can atomically store. > Sorry, Could you explain what you advised? I think it is hard to fix this problem by adding a variant, because it is hard to avoid loading a word of the mask before nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); and then loading another word of the mask after tsk->mems_allowed = *newmems; unless we use lock. Maybe we need a rw-lock to protect task->mems_allowed. -- 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>