On Thu 21-07-16 21:58:23, zhong jiang wrote: > On 2016/7/21 21:40, Michal Hocko wrote: > > On Thu 21-07-16 21:25:38, zhong jiang wrote: > >> On 2016/7/21 20:55, Michal Hocko wrote: > > [...] > >>> OK, now I understand what you mean. So you mean that a different process > >>> initiates the migration while this path copies to pte. That is certainly > >>> possible but I still fail to see what is the problem about that. > >>> huge_pte_alloc will return the identical pte whether it is regular or > >>> migration one. So what exactly is the problem? > >>> > >> copy_hugetlb_page_range obtain the shared dst_pte, it may be not equal > >> to the src_pte. The dst_pte can come from other process sharing the > >> mapping. > > So you mean that the parent doesn't have the shared pte while the child > > would get one? > > > no, parent must have the shared pte because the the child copy the > parent. but parent is not the only source pte we can get. when we > scan the maping->i_mmap, firstly ,it can obtain a shared pte from > other process. but I am not sure. But then all the shared ptes should be identical, no? Or am I missing something? -- Michal Hocko SUSE Labs -- 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>