From bd2753b2dda7bb43c7468826de75f49c6a7e8965 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 6 Jun 2012 10:55:40 -0700 Subject: [PATCH] x86/mm: Only add extra pages count for the first memory range during pre-allocation early page table space Robin found this regression: | I just tried to boot an 8TB system. It fails very early in boot with: | Kernel panic - not syncing: Cannot find space for the kernel page tables git bisect commit 722bc6b16771ed80871e1fd81c86d3627dda2ac8. A git revert of that commit does boot past that point on the 8TB configuration. That commit will add up extra pages for all memory range even above 4g. Try to limit that extra page count adding to first entry only. Bisected-by: Robin Holt Tested-by: Robin Holt Signed-off-by: Yinghai Lu Cc: WANG Cong Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/CAE9FiQUj3wyzQxtq9yzBNc9u220p8JZ1FYHG7t%3DMOzJ%3D9BZMYA@mail.gmail.com Signed-off-by: Ingo Molnar --- arch/x86/mm/init.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 97141c26a13a..bc4e9d84157f 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -62,7 +62,8 @@ static void __init find_early_table_space(struct map_range *mr, unsigned long en extra += PMD_SIZE; #endif /* The first 2/4M doesn't use large pages. */ - extra += mr->end - mr->start; + if (mr->start < PMD_SIZE) + extra += mr->end - mr->start; ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT; } else -- 2.20.1