On 2014?11?24? 22:32, Catalin Marinas wrote:

On Fri, Nov 21, 2014 at 08:27:40AM +0000, zhichang.yuan at linaro.org wrote:

quoted

From: "zhichang.yuan" <redacted>

For 64K page system, after mapping a PMD section, the corresponding initial
page table is not needed any more. That page can be freed.

Signed-off-by: Zhichang Yuan <redacted>
---
 arch/arm64/mm/mmu.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index f4f8b50..12a336b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c

@@ -191,8 +191,11 @@ static void __init alloc_init_pmd(pud_t *pud, unsigned long addr,
 			 * Check for previous table entries created during
 			 * boot (__create_page_tables) and flush them.
 			 */
-			if (!pmd_none(old_pmd))
+			if (!pmd_none(old_pmd)) {
 				flush_tlb_all();
+				if (pmd_table(old_pmd))
+					memblock_free(pte_pfn(pmd_pte(old_pmd)) << PAGE_SHIFT, PAGE_SIZE);
+			}

For consistency with alloc_init_pud(), could you do:

	phys_addr_t table = __pa(pte_offset(&old_pmd, 0));
	memblock_free(table, PAGE_SIZE);

Just as Laura comments, the pte_offset will convert the PA to VA, and then convert  VA to PA. It seems to be
verbose. That is why i use pte_pfn. Anyway, the consistency is better, i will revise it.

Since you are at this, for alloc_init_pud() could you please move the
flush_tlb_all() before memblock_free()? Theoretical problem really but
it's nice for consistency.

Thanks.

As for this issue, i have a small question.  Since the new PMD entry had been set by set_pmd, why not do the
tlb flush as soon as we can?

Thanks!