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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/alpha/mm
parent46dea3d092d23a58b42499cc8a21de0fad079f4a (diff)
downloadlinux-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/alpha/mm')
-rw-r--r--arch/alpha/mm/remap.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/arch/alpha/mm/remap.c b/arch/alpha/mm/remap.c
index 19817ad3d89b..a78356c3ead5 100644
--- a/arch/alpha/mm/remap.c
+++ b/arch/alpha/mm/remap.c
@@ -2,7 +2,6 @@
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
-/* called with the page_table_lock held */
static inline void
remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
unsigned long phys_addr, unsigned long flags)
@@ -31,7 +30,6 @@ remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
} while (address && (address < end));
}
-/* called with the page_table_lock held */
static inline int
remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
unsigned long phys_addr, unsigned long flags)
@@ -46,7 +44,7 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
if (address >= end)
BUG();
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,
@@ -70,7 +68,6 @@ __alpha_remap_area_pages(unsigned long address, unsigned long phys_addr,
flush_cache_all();
if (address >= end)
BUG();
- spin_lock(&init_mm.page_table_lock);
do {
pmd_t *pmd;
pmd = pmd_alloc(&init_mm, dir, address);
@@ -84,7 +81,6 @@ __alpha_remap_area_pages(unsigned long address, unsigned long phys_addr,
address = (address + PGDIR_SIZE) & PGDIR_MASK;
dir++;
} while (address && (address < end));
- spin_unlock(&init_mm.page_table_lock);
return error;
}