Commit b462705a authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

[PATCH] mm: arches skip ptlock 



Convert those few architectures which are calling pud_alloc, pmd_alloc,
pte_alloc_map on a user mm, not to take the page_table_lock first, nor drop it
after.  Each of these can continue to use pte_alloc_map, no need to change
over to pte_alloc_map_lock, they're neither racy nor swappable.

In the sparc64 io_remap_pfn_range, flush_tlb_range then falls outside of the
page_table_lock: that's okay, on sparc64 it's like flush_tlb_mm, and that has
always been called from outside of page_table_lock in dup_mmap.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c74df32c

arch/arm/mm/mm-armv.c

+0 −14
Original line number Diff line number Diff line
@@ -179,11 +179,6 @@ pgd_t *get_pgd_slow(struct mm_struct *mm) 
	clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));



	if (!vectors_high()) {

		/*

		 * This lock is here just to satisfy pmd_alloc and pte_lock

		 */

		spin_lock(&mm->page_table_lock);



		/*

		 * On ARM, first page must always be allocated since it

		 * contains the machine vectors.
@@ -201,23 +196,14 @@ pgd_t *get_pgd_slow(struct mm_struct *mm) 
		set_pte(new_pte, *init_pte);

		pte_unmap_nested(init_pte);

		pte_unmap(new_pte);



		spin_unlock(&mm->page_table_lock);

	}



	return new_pgd;



no_pte:

	spin_unlock(&mm->page_table_lock);

	pmd_free(new_pmd);

	free_pages((unsigned long)new_pgd, 2);

	return NULL;



no_pmd:

	spin_unlock(&mm->page_table_lock);

	free_pages((unsigned long)new_pgd, 2);

	return NULL;



no_pgd:

	return NULL;

}

arch/arm26/mm/memc.c

+0 −15
Original line number Diff line number Diff line
@@ -78,12 +78,6 @@ pgd_t *get_pgd_slow(struct mm_struct *mm) 
	if (!new_pgd)

		goto no_pgd;



	/*

	 * This lock is here just to satisfy pmd_alloc and pte_lock

         * FIXME: I bet we could avoid taking it pretty much altogether

	 */

	spin_lock(&mm->page_table_lock);



	/*

	 * On ARM, first page must always be allocated since it contains

	 * the machine vectors.
@@ -113,23 +107,14 @@ pgd_t *get_pgd_slow(struct mm_struct *mm) 
	memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,

		(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));



	spin_unlock(&mm->page_table_lock);



	/* update MEMC tables */

	cpu_memc_update_all(new_pgd);

	return new_pgd;



no_pte:

	spin_unlock(&mm->page_table_lock);

	pmd_free(new_pmd);

	free_pgd_slow(new_pgd);

	return NULL;



no_pmd:

	spin_unlock(&mm->page_table_lock);

	free_pgd_slow(new_pgd);

	return NULL;



no_pgd:

	return NULL;

}

arch/sparc/mm/generic.c

+1 −3
Original line number Diff line number Diff line
@@ -81,9 +81,8 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 
	dir = pgd_offset(mm, from);

	flush_cache_range(vma, beg, end);



	spin_lock(&mm->page_table_lock);

	while (from < end) {

		pmd_t *pmd = pmd_alloc(current->mm, dir, from);

		pmd_t *pmd = pmd_alloc(mm, dir, from);

		error = -ENOMEM;

		if (!pmd)

			break;
@@ -93,7 +92,6 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 
		from = (from + PGDIR_SIZE) & PGDIR_MASK;

		dir++;

	}

	spin_unlock(&mm->page_table_lock);



	flush_tlb_range(vma, beg, end);

	return error;

arch/sparc64/mm/generic.c

+2 −4
Original line number Diff line number Diff line
@@ -135,9 +135,8 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 
	dir = pgd_offset(mm, from);

	flush_cache_range(vma, beg, end);



	spin_lock(&mm->page_table_lock);

	while (from < end) {

		pud_t *pud = pud_alloc(current->mm, dir, from);

		pud_t *pud = pud_alloc(mm, dir, from);

		error = -ENOMEM;

		if (!pud)

			break;
@@ -147,8 +146,7 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 
		from = (from + PGDIR_SIZE) & PGDIR_MASK;

		dir++;

	}

	flush_tlb_range(vma, beg, end);

	spin_unlock(&mm->page_table_lock);



	flush_tlb_range(vma, beg, end);

	return error;

}

arch/um/kernel/skas/mmu.c

+0 −3
Original line number Diff line number Diff line
@@ -28,7 +28,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc, 
	pmd_t *pmd;

	pte_t *pte;



	spin_lock(&mm->page_table_lock);

	pgd = pgd_offset(mm, proc);

	pud = pud_alloc(mm, pgd, proc);

	if (!pud)
@@ -63,7 +62,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc, 
	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));

	*pte = pte_mkexec(*pte);

	*pte = pte_wrprotect(*pte);

	spin_unlock(&mm->page_table_lock);

	return(0);



 out_pmd:
@@ -71,7 +69,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc, 
 out_pte:

	pmd_free(pmd);

 out:

	spin_unlock(&mm->page_table_lock);

	return(-ENOMEM);

}

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