On Tue, Mar 6, 2012 at 8:16 AM, tip-bot for WANG Cong <xiyou.wangcong@xxxxxxxxx> wrote: > Commit-ID: 722bc6b16771ed80871e1fd81c86d3627dda2ac8 > Gitweb: http://git.kernel.org/tip/722bc6b16771ed80871e1fd81c86d3627dda2ac8 > Author: WANG Cong <xiyou.wangcong@xxxxxxxxx> > AuthorDate: Mon, 5 Mar 2012 15:05:13 -0800 > Committer: Ingo Molnar <mingo@xxxxxxx> > CommitDate: Tue, 6 Mar 2012 09:38:26 +0100 > > x86/mm: Fix the size calculation of mapping tables > > For machines that enable PSE, the first 2/4M memory region still uses > 4K pages, so needs more PTEs in this case, but > find_early_table_space() doesn't count this. > > This patch fixes it. > > The bug was found via code review, no misbehavior of the kernel > was observed. > > Signed-off-by: WANG Cong <xiyou.wangcong@xxxxxxxxx> > Cc: Yinghai Lu <yinghai@xxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: <ianfang.cn@xxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Link: http://lkml.kernel.org/n/tip-kq6a00qe33h7c7ais2xsywnh@xxxxxxxxxxxxxx > Signed-off-by: Ingo Molnar <mingo@xxxxxxx> > --- > arch/x86/mm/init.c | 21 ++++++++++++--------- > 1 files changed, 12 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index 6cabf65..2e92fdc 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -30,8 +30,14 @@ int direct_gbpages > #endif > ; > > -static void __init find_early_table_space(unsigned long end, int use_pse, > - int use_gbpages) > +struct map_range { > + unsigned long start; > + unsigned long end; > + unsigned page_size_mask; > +}; > + > +static void __init find_early_table_space(struct map_range *mr, unsigned long end, > + int use_pse, int use_gbpages) > { > unsigned long puds, pmds, ptes, tables, start = 0, good_end = end; > phys_addr_t base; > @@ -56,6 +62,9 @@ static void __init find_early_table_space(unsigned long end, int use_pse, > #ifdef CONFIG_X86_32 > extra += PMD_SIZE; > #endif > + /* The first 2/4M doesn't use large pages. */ > + extra += mr->end - mr->start; > + Something wrong here, you need to check if this MR is really cover first 2/4M ... something like Index: linux-2.6/arch/x86/mm/init.c =================================================================== --- linux-2.6.orig/arch/x86/mm/init.c +++ linux-2.6/arch/x86/mm/init.c @@ -63,7 +63,8 @@ static void __init find_early_table_spac 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 otherwise, for system with 512G or more. page table for [4G, 512g) may have preallocate more but only use little. Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html