Messages in this thread Patch in this message | | | Date | Sun, 1 May 2011 19:12:04 +0200 | From | Tejun Heo <> | Subject | [PATCH REPOST tip:x86/urgent] x86, NUMA: Fix empty memblk detection in numa_cleanup_meminfo() |
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From: Yinghai Lu <yinghai@kernel.org>
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 ==.
tj: Extracted the actual fix from the original patch and rewrote patch description.
Signed-off-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org> --- Here's the patch with updated description. Thank you.
arch/x86/mm/numa_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: work/arch/x86/mm/numa_64.c =================================================================== --- work.orig/arch/x86/mm/numa_64.c +++ work/arch/x86/mm/numa_64.c @@ -191,7 +191,7 @@ int __init numa_cleanup_meminfo(struct n 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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