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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:21 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:40 -0700
commit872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch)
tree1dfc8b9f2754bdfff645188e497865c00201d535 /arch/ppc/mm
parent46dea3d092d23a58b42499cc8a21de0fad079f4a (diff)
downloadlinux-linaro-stable-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.gz
[PATCH] mm: init_mm without ptlock
First step in pushing down the page_table_lock. init_mm.page_table_lock has been used throughout the architectures (usually for ioremap): not to serialize kernel address space allocation (that's usually vmlist_lock), but because pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it. Reverse that: don't lock or unlock init_mm.page_table_lock in any of the architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take and drop it when allocating a new one, to check lest a racing task already did. Similarly no page_table_lock in vmalloc's map_vm_area. Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle user mms, which are converted only by a later patch, for now they have to lock differently according to whether or not it's init_mm. If sources get muddled, there's a danger that an arch source taking init_mm.page_table_lock will be mixed with common source also taking it (or neither take it). So break the rules and make another change, which should break the build for such a mismatch: remove the redundant mm arg from pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13). Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64 used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64 map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free took page_table_lock for no good reason. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/ppc/mm')
-rw-r--r--arch/ppc/mm/4xx_mmu.c4
-rw-r--r--arch/ppc/mm/pgtable.c4
2 files changed, 1 insertions, 7 deletions
diff --git a/arch/ppc/mm/4xx_mmu.c b/arch/ppc/mm/4xx_mmu.c
index b7bcbc232f39..4d006aa1a0d1 100644
--- a/arch/ppc/mm/4xx_mmu.c
+++ b/arch/ppc/mm/4xx_mmu.c
@@ -110,13 +110,11 @@ unsigned long __init mmu_mapin_ram(void)
pmd_t *pmdp;
unsigned long val = p | _PMD_SIZE_16M | _PAGE_HWEXEC | _PAGE_HWWRITE;
- spin_lock(&init_mm.page_table_lock);
pmdp = pmd_offset(pgd_offset_k(v), v);
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
- spin_unlock(&init_mm.page_table_lock);
v += LARGE_PAGE_SIZE_16M;
p += LARGE_PAGE_SIZE_16M;
@@ -127,10 +125,8 @@ unsigned long __init mmu_mapin_ram(void)
pmd_t *pmdp;
unsigned long val = p | _PMD_SIZE_4M | _PAGE_HWEXEC | _PAGE_HWWRITE;
- spin_lock(&init_mm.page_table_lock);
pmdp = pmd_offset(pgd_offset_k(v), v);
pmd_val(*pmdp) = val;
- spin_unlock(&init_mm.page_table_lock);
v += LARGE_PAGE_SIZE_4M;
p += LARGE_PAGE_SIZE_4M;
diff --git a/arch/ppc/mm/pgtable.c b/arch/ppc/mm/pgtable.c
index 43505b1fc5d8..6ea9185fd120 100644
--- a/arch/ppc/mm/pgtable.c
+++ b/arch/ppc/mm/pgtable.c
@@ -280,18 +280,16 @@ map_page(unsigned long va, phys_addr_t pa, int flags)
pte_t *pg;
int err = -ENOMEM;
- spin_lock(&init_mm.page_table_lock);
/* Use upper 10 bits of VA to index the first level map */
pd = pmd_offset(pgd_offset_k(va), va);
/* Use middle 10 bits of VA to index the second-level map */
- pg = pte_alloc_kernel(&init_mm, pd, va);
+ pg = pte_alloc_kernel(pd, va);
if (pg != 0) {
err = 0;
set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, __pgprot(flags)));
if (mem_init_done)
flush_HPTE(0, va, pmd_val(*pd));
}
- spin_unlock(&init_mm.page_table_lock);
return err;
}