diff options
author | Hugh Dickins <hugh@veritas.com> | 2005-10-30 01:16:21 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-30 04:40:40 (GMT) |
commit | 872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch) | |
tree | 1dfc8b9f2754bdfff645188e497865c00201d535 /arch/arm/mm | |
parent | 46dea3d092d23a58b42499cc8a21de0fad079f4a (diff) | |
download | linux-fsl-qoriq-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.xz |
[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.c | 6 | ||||
-rw-r--r-- | arch/arm/mm/ioremap.c | 4 |
2 files changed, 2 insertions, 8 deletions
diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c index 82f4d5e..47b0b76 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 6fb1258..0f128c2 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; } |