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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/arm/mm
parent46dea3d092d23a58b42499cc8a21de0fad079f4a (diff)
[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/arm/mm')
-rw-r--r--arch/arm/mm/consistent.c6
-rw-r--r--arch/arm/mm/ioremap.c4
2 files changed, 2 insertions, 8 deletions
diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
index 82f4d5e27c5..47b0b767f08 100644
--- a/arch/arm/mm/consistent.c
+++ b/arch/arm/mm/consistent.c
@@ -397,8 +397,6 @@ static int __init consistent_init(void)
pte_t *pte;
int ret = 0;
- spin_lock(&init_mm.page_table_lock);
-
do {
pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
@@ -409,7 +407,7 @@ static int __init consistent_init(void)
}
WARN_ON(!pmd_none(*pmd));
- pte = pte_alloc_kernel(&init_mm, pmd, CONSISTENT_BASE);
+ pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
if (!pte) {
printk(KERN_ERR "%s: no pte tables\n", __func__);
ret = -ENOMEM;
@@ -419,8 +417,6 @@ static int __init consistent_init(void)
consistent_pte = pte;
} while (0);
- spin_unlock(&init_mm.page_table_lock);
-
return ret;
}
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 6fb1258df1b..0f128c28fee 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -75,7 +75,7 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
do {
- pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
+ pte_t * pte = pte_alloc_kernel(pmd, address);
if (!pte)
return -ENOMEM;
remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
@@ -97,7 +97,6 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
phys_addr -= address;
dir = pgd_offset(&init_mm, address);
BUG_ON(address >= end);
- spin_lock(&init_mm.page_table_lock);
do {
pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
if (!pmd) {
@@ -114,7 +113,6 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
dir++;
} while (address && (address < end));
- spin_unlock(&init_mm.page_table_lock);
flush_cache_vmap(start, end);
return err;
}