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 722bc6b167.

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 <holt@sgi.com>
Tested-by: Robin Holt <holt@sgi.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/CAE9FiQUj3wyzQxtq9yzBNc9u220p8JZ1FYHG7t%3DMOzJ%3D9BZMYA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yinghai Lu 2012-06-06 10:55:40 -07:00 committed by Ingo Molnar
parent 743628e868
commit bd2753b2dd
1 changed files with 2 additions and 1 deletions

View File

@ -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