From: liu ping fan <qemulist@gmail.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, linux-mm@kvack.org, Peter Zijlstra <peterz@infradead.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS Date: Fri, 28 Feb 2014 10:54:33 +0800 [thread overview] Message-ID: <CAJnKYQnK57Z-FVVXTJ9u5ijTh8QFCw1PnEj_526Q4DzeyyWRTw@mail.gmail.com> (raw) In-Reply-To: <20140227154104.4e3572f1d9e2692d431d1a4e@linux-foundation.org> On Fri, Feb 28, 2014 at 7:41 AM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Wed, 26 Feb 2014 13:22:16 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote: > >> Andrew Morton <akpm@linux-foundation.org> writes: >> >> > On Wed, 5 Feb 2014 09:25:46 +0800 Liu Ping Fan <qemulist@gmail.com> 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@linux.vnet.ibm.com >> >> #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@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
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From: liu ping fan <qemulist@gmail.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org>, linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS Date: Fri, 28 Feb 2014 10:54:33 +0800 [thread overview] Message-ID: <CAJnKYQnK57Z-FVVXTJ9u5ijTh8QFCw1PnEj_526Q4DzeyyWRTw@mail.gmail.com> (raw) In-Reply-To: <20140227154104.4e3572f1d9e2692d431d1a4e@linux-foundation.org> On Fri, Feb 28, 2014 at 7:41 AM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Wed, 26 Feb 2014 13:22:16 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote: > >> Andrew Morton <akpm@linux-foundation.org> writes: >> >> > On Wed, 5 Feb 2014 09:25:46 +0800 Liu Ping Fan <qemulist@gmail.com> 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@linux.vnet.ibm.com >> >> #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. >
next prev parent reply other threads:[~2014-02-28 2:54 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-02-05 1:25 [PATCH] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS Liu Ping Fan 2014-02-05 8:11 ` Peter Zijlstra 2014-02-06 0:53 ` liu ping fan 2014-02-13 23:20 ` Andrew Morton 2014-02-13 23:20 ` Andrew Morton 2014-02-26 7:52 ` Aneesh Kumar K.V 2014-02-26 7:52 ` Aneesh Kumar K.V 2014-02-27 23:41 ` Andrew Morton 2014-02-27 23:41 ` Andrew Morton 2014-02-28 2:54 ` liu ping fan [this message] 2014-02-28 2:54 ` liu ping fan 2014-02-28 4:47 ` Aneesh Kumar K.V 2014-02-28 4:47 ` Aneesh Kumar K.V 2014-02-28 5:28 ` [PATCH V2] " Aneesh Kumar K.V 2014-02-28 5:28 ` Aneesh Kumar K.V 2014-02-28 5:28 ` Aneesh Kumar K.V 2014-02-28 6:36 ` [PATCH] " liu ping fan 2014-02-28 6:36 ` liu ping fan 2014-02-28 9:04 ` Aneesh Kumar K.V 2014-02-28 9:04 ` Aneesh Kumar K.V 2014-02-26 7:32 ` Aneesh Kumar K.V 2014-02-26 8:21 ` liu ping fan
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