On Fri, Feb 28, 2014 at 7:41 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > 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 think Aneesh was talking about the chunk of patch, which modified the file "page-flags-layout.h". I tried to collapse and simplify the logic, but it will incur that LAST_CPUPID_WIDTH depends on CONFIG_NUMA_BALANCING. It is an error since we need LAST_CPUPID_WIDTH even without CONFIG_NUMA_BALANCING. (Sorry, I compiled and run kernel, but not find this). Thanks and best regards, Fan > 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>