So when we unmap kernel memory range then we also check whether a PUD is completely clear, and free it and clear the PGD entry.
This complicates PGD management, so don't do this. We can keep the PGD mapped and the PUD table all clear - it's only a single 4K page per 512 GB of memory mapped. Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Waiman Long <[email protected]> Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/pageattr.c | 15 --------------- 1 file changed, 15 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 70d221fe2eb4..997fc97e9072 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -717,18 +717,6 @@ static bool try_to_free_pmd_page(pmd_t *pmd) return true; } -static bool try_to_free_pud_page(pud_t *pud) -{ - int i; - - for (i = 0; i < PTRS_PER_PUD; i++) - if (!pud_none(pud[i])) - return false; - - free_page((unsigned long)pud); - return true; -} - static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end) { pte_t *pte = pte_offset_kernel(pmd, start); @@ -847,9 +835,6 @@ static void unmap_pgd_range(pgd_t *root, unsigned long addr, unsigned long end) pgd_t *pgd_entry = root + pgd_index(addr); unmap_pud_range(pgd_entry, addr, end); - - if (try_to_free_pud_page((pud_t *)pgd_page_vaddr(*pgd_entry))) - pgd_clear(pgd_entry); } static int alloc_pte_page(pmd_t *pmd) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
