From 42cf5f0281f6b640d4a87fe5c92373a7e73c798c 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 4c94dab537bcc86ad95f4be935083fe416c79df6. 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 97141c26a13ac..bc4e9d84157fc 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 -- 2.39.5