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Commit 9a3dc780 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86: cpa: simplify locking 



further simplify cpa locking: since the largepage-split is a
slowpath, use the pgd_lock for the whole operation, intead
of the mmap_sem.

This also makes it suitable for DEBUG_PAGEALLOC purposes again.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7afe15b9

arch/x86/mm/pageattr_32.c

+5 −7
Original line number Diff line number Diff line
@@ -37,9 +37,8 @@ pte_t *lookup_address(unsigned long address, int *level) 
	return pte_offset_kernel(pmd, address);

}



static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)

static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)

{

	unsigned long flags;

	struct page *page;



	/* change init_mm */
@@ -47,7 +46,6 @@ static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
	if (SHARED_KERNEL_PMD)

		return;



	spin_lock_irqsave(&pgd_lock, flags);

	for (page = pgd_list; page; page = (struct page *)page->index) {

		pgd_t *pgd;

		pud_t *pud;
@@ -58,12 +56,12 @@ static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
		pmd = pmd_offset(pud, address);

		set_pte_atomic((pte_t *)pmd, pte);

	}

	spin_unlock_irqrestore(&pgd_lock, flags);

}



static int split_large_page(pte_t *kpte, unsigned long address)

{

	pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));

	unsigned long flags;

	unsigned long addr;

	pte_t *pbase, *tmp;

	struct page *base;
@@ -73,7 +71,7 @@ static int split_large_page(pte_t *kpte, unsigned long address) 
	if (!base)

		return -ENOMEM;



	down_write(&init_mm.mmap_sem);

	spin_lock_irqsave(&pgd_lock, flags);

	/*

	 * Check for races, another CPU might have split this page

	 * up for us already:
@@ -95,11 +93,11 @@ static int split_large_page(pte_t *kpte, unsigned long address) 
	/*

	 * Install the new, split up pagetable:

	 */

	set_pmd_pte(kpte, address, mk_pte(base, ref_prot));

	__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));

	base = NULL;



out_unlock:

	up_write(&init_mm.mmap_sem);

	spin_unlock_irqrestore(&pgd_lock, flags);



	if (base)

		__free_pages(base, 0);