On Wed, 26 Feb 2014 13:22:16 +0530 "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote: > Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > > > 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 > > > > All these are already in 3.14 ? Yes. > > are 3.15-rc1 material? > > > > We should push the first hunk to 3.14. I will wait for Liu to redo the > patch. BTW this should happen only when SPARSE_VMEMMAP is not > specified. Srikar had reported the issue here > > http://mid.gmane.org/20140219180200.GA29257@xxxxxxxxxxxxxxxxxx > > #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) > #define SECTIONS_WIDTH SECTIONS_SHIFT > #else > #define SECTIONS_WIDTH 0 > #endif > I'm lost. What patch are you talking about? The first hunk of what? I assume we're talking about mm-numa-bugfix-for-last_cpupid_not_in_page_flags.patch, which I had queued for 3.14. I'll put it on hold until there's some clarity here. -- 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>