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authorHugh Dickins <hugh@veritas.com>2005-10-29 21:16:21 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-30 00:40:40 -0400
commit872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch)
tree1dfc8b9f2754bdfff645188e497865c00201d535 /arch/mips/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/mips/mm')
-rw-r--r--arch/mips/mm/ioremap.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/mips/mm/ioremap.c b/arch/mips/mm/ioremap.c
index 9c44ca70befa..3101d1db5592 100644
--- a/arch/mips/mm/ioremap.c
+++ b/arch/mips/mm/ioremap.c
@@ -55,7 +55,7 @@ static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
55 if (address >= end) 55 if (address >= end)
56 BUG(); 56 BUG();
57 do { 57 do {
58 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address); 58 pte_t * pte = pte_alloc_kernel(pmd, address);
59 if (!pte) 59 if (!pte)
60 return -ENOMEM; 60 return -ENOMEM;
61 remap_area_pte(pte, address, end - address, address + phys_addr, flags); 61 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
@@ -77,7 +77,6 @@ static int remap_area_pages(unsigned long address, phys_t phys_addr,
77 flush_cache_all(); 77 flush_cache_all();
78 if (address >= end) 78 if (address >= end)
79 BUG(); 79 BUG();
80 spin_lock(&init_mm.page_table_lock);
81 do { 80 do {
82 pud_t *pud; 81 pud_t *pud;
83 pmd_t *pmd; 82 pmd_t *pmd;
@@ -96,7 +95,6 @@ static int remap_area_pages(unsigned long address, phys_t phys_addr,
96 address = (address + PGDIR_SIZE) & PGDIR_MASK; 95 address = (address + PGDIR_SIZE) & PGDIR_MASK;
97 dir++; 96 dir++;
98 } while (address && (address < end)); 97 } while (address && (address < end));
99 spin_unlock(&init_mm.page_table_lock);
100 flush_tlb_all(); 98 flush_tlb_all();
101 return error; 99 return error;
102} 100}