From 2be19102b71c1a45d37fec50303791daa1a06869 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Sun, 1 May 2011 19:12:04 +0200 Subject: [PATCH] x86, NUMA: Fix empty memblk detection in numa_cleanup_meminfo() numa_cleanup_meminfo() trims each memblk between low (0) and high (max_pfn) limits and discards empty ones. However, the emptiness detection incorrectly used equality test. If the start of a memblk is higher than max_pfn, it is empty but fails the equality test and doesn't get discarded. The condition triggers when max_pfn is lower than start of a NUMA node and results in memory misconfiguration - leading to WARN_ON()s and other funnies. The bug was discovered in devel branch where 32bit too uses this code path for NUMA init. If a node is above the addressing limit, max_pfn ends up lower than the node triggering this problem. The failure hasn't been observed on x86-64 but is still possible with broken hardware e820/NUMA info. As the fix is very low risk, it would be better to apply it even for 64bit. Fix it by using >= instead of ==. Signed-off-by: Yinghai Lu [ Extracted the actual fix from the original patch and rewrote patch description. ] Signed-off-by: Tejun Heo Link: http://lkml.kernel.org/r/20110501171204.GO29280@htj.dyndns.org Signed-off-by: Ingo Molnar --- arch/x86/mm/numa_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c index e8c00cc72033..85b52fc03084 100644 --- a/arch/x86/mm/numa_64.c +++ b/arch/x86/mm/numa_64.c @@ -306,7 +306,7 @@ int __init numa_cleanup_meminfo(struct numa_meminfo *mi) bi->end = min(bi->end, high); /* and there's no empty block */ - if (bi->start == bi->end) { + if (bi->start >= bi->end) { numa_remove_memblk_from(i--, mi); continue; }