Re: [PATCH V3] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS
From: Peter Zijlstra <peterz@infradead.org>
Date: 2014-02-28 11:32:06
Also in:
linux-mm, lkml
On Fri, Feb 28, 2014 at 02:32:02PM +0530, Aneesh Kumar K.V wrote:
From: Liu Ping Fan <redacted> 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. This happen with CONFIG_SPARSE_VMEMMAP disabled Signed-off-by: Liu Ping Fan <redacted> Signed-off-by: Aneesh Kumar K.V <redacted>
Acked-by: Peter Zijlstra <peterz@infradead.org>
quoted hunk ↗ jump to hunk
--- include/linux/mm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/include/linux/mm.h b/include/linux/mm.h index f28f46eade6a..86245839c9fa 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h@@ -757,7 +757,7 @@ static inline bool __cpupid_match_pid(pid_t task_pid, int cpupid) #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS static inline int page_cpupid_xchg_last(struct page *page, int cpupid) { - return xchg(&page->_last_cpupid, cpupid); + return xchg(&page->_last_cpupid, cpupid & LAST_CPUPID_MASK); } static inline int page_cpupid_last(struct page *page)@@ -766,7 +766,7 @@ static inline int page_cpupid_last(struct page *page) } static inline void page_cpupid_reset_last(struct page *page) { - page->_last_cpupid = -1; + page->_last_cpupid = -1 & LAST_CPUPID_MASK; } #else static inline int page_cpupid_last(struct page *page)-- 1.8.3.2