From: Peter Zijlstra <[email protected]> Use the other page_table_lock pattern; this removes the free from under the lock, reducing worst case hold times and makes it a leaf lock.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/kaiser.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c index 0282169ede18..0ff502fa655b 100644 --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -196,11 +196,13 @@ static pte_t *kaiser_shadow_pagetable_walk(unsigned long address, return NULL; spin_lock(&shadow_table_allocation_lock); - if (p4d_none(*p4d)) + if (p4d_none(*p4d)) { set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page))); - else - free_page(new_pud_page); + new_pud_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pud_page) + free_page(new_pud_page); } pud = pud_offset(p4d, address); @@ -215,11 +217,13 @@ static pte_t *kaiser_shadow_pagetable_walk(unsigned long address, return NULL; spin_lock(&shadow_table_allocation_lock); - if (pud_none(*pud)) + if (pud_none(*pud)) { set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page))); - else - free_page(new_pmd_page); + new_pmd_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pmd_page) + free_page(new_pmd_page); } pmd = pmd_offset(pud, address); @@ -234,11 +238,13 @@ static pte_t *kaiser_shadow_pagetable_walk(unsigned long address, return NULL; spin_lock(&shadow_table_allocation_lock); - if (pmd_none(*pmd)) + if (pmd_none(*pmd)) { set_pmd(pmd, __pmd(_KERNPG_TABLE | __pa(new_pte_page))); - else - free_page(new_pte_page); + new_pte_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pte_page) + free_page(new_pte_page); } pte = pte_offset_kernel(pmd, address); -- 2.14.1
