From 12710a56cb56e81bd8f457cc2f50c2ebfc0cb390 Mon Sep 17 00:00:00 2001 From: Bob Picco Date: Fri, 8 Jun 2007 13:47:00 -0700 Subject: [PATCH] fix sysrq-m oops We aren't sampling for holes in memory. Thus we encounter a section hole with empty section map pointer for SPARSEMEM and OOPs for show_mem. This issue has been seen in 2.6.21, current git and current mm. The patch below is for mainline and mm. It was boot tested for SPARSEMEM, current VMEMMAP of Andy's in mm ml and DISCONTIGMEM. A slightly different patch will be posted to stable for 2.6.21. Previous to commit f0a5a58aa812b31fd9f197c4ba48245942364eae memory_present was called for node_start_pfn to node_end_pfn. This would cover the hole(s) with reserved pages and valid sections. Most SPARSEMEM supported arches do a pfn_valid check in show_mem before computing the page structure address. This issue was brought to my attention on IRC by Arnaldo Carvalho de Melo. Thanks to Arnaldo for testing. Signed-off-by: Bob Picco Cc: Chuck Ebbert Cc: Andi Kleen Cc: Arnaldo Carvalho de Melo Acked-by: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/mm/init.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c index 1ad5111aec38..efb6e845114e 100644 --- a/arch/x86_64/mm/init.c +++ b/arch/x86_64/mm/init.c @@ -79,6 +79,8 @@ void show_mem(void) if (unlikely(i % MAX_ORDER_NR_PAGES == 0)) { touch_nmi_watchdog(); } + if (!pfn_valid(pgdat->node_start_pfn + i)) + continue; page = pfn_to_page(pgdat->node_start_pfn + i); total++; if (PageReserved(page)) -- 2.20.1