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[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: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hugh Dickins 2005-10-29 18:16:24 -07:00 committed by Linus Torvalds
parent c74df32c72
commit b462705ac6
5 changed files with 3 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/arm/mm/mm-armv.c
View File

@ -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;
}

15
arch/arm26/mm/memc.c
View File

@ -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;
}

4
arch/sparc/mm/generic.c
View File

@ -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;

6
arch/sparc64/mm/generic.c
View File

@ -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;
}

3
arch/um/kernel/skas/mmu.c
View File

@ -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);
}