[tip:x86/urgent] x86, NUMA: Fix empty memblk detection in numa_cleanup_meminfo()
From: tip-bot for Yinghai Lu
Date: Sun May 01 2011 - 13:44:44 EST
Commit-ID: 2be19102b71c1a45d37fec50303791daa1a06869
Gitweb: http://git.kernel.org/tip/2be19102b71c1a45d37fec50303791daa1a06869
Author: Yinghai Lu <yinghai@xxxxxxxxxx>
AuthorDate: Sun, 1 May 2011 19:12:04 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sun, 1 May 2011 19:15:11 +0200
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 <yinghai@xxxxxxxxxx>
[ Extracted the actual fix from the original patch and rewrote patch description. ]
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20110501171204.GO29280@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/mm/numa_64.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index e8c00cc..85b52fc 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;
}
--
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