On Wed, 5 Feb 2014 09:25:46 +0800 Liu Ping Fan <qemulist@xxxxxxxxx> wrote: > When doing some numa tests on powerpc, I triggered an oops bug. I find > it is caused by using page->_last_cpupid. It should be initialized as > "-1 & LAST_CPUPID_MASK", but not "-1". Otherwise, in task_numa_fault(), > we will miss the checking (last_cpupid == (-1 & LAST_CPUPID_MASK)). > And finally cause an oops bug in task_numa_group(), since the online cpu is > less than possible cpu. I grabbed this. I added this to the changelog: : PPC needs the LAST_CPUPID_NOT_IN_PAGE_FLAGS case because ppc needs to : support a large physical address region, up to 2^46 but small section size : (2^24). So when NR_CPUS grows up, it is easily to cause : not-in-page-flags. to hopefully address Peter's observation. How should we proceed with this? I'm getting the impression that numa balancing on ppc is a dead duck in 3.14, so perhaps this and powerpc-mm-add-new-set-flag-argument-to-pte-pmd-update-function.patch mm-dirty-accountable-change-only-apply-to-non-prot-numa-case.patch mm-use-ptep-pmdp_set_numa-for-updating-_page_numa-bit.patch are 3.15-rc1 material? -- 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>