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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/parisc
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/parisc')
-rw-r--r--arch/parisc/kernel/pci-dma.c2
-rw-r--r--arch/parisc/mm/ioremap.c6
2 files changed, 3 insertions, 5 deletions
diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index ae6213d71670..f94a02ef3d95 100644
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -114,7 +114,7 @@ static inline int map_pmd_uncached(pmd_t * pmd, unsigned long vaddr,
114 if (end > PGDIR_SIZE) 114 if (end > PGDIR_SIZE)
115 end = PGDIR_SIZE; 115 end = PGDIR_SIZE;
116 do { 116 do {
117 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, vaddr); 117 pte_t * pte = pte_alloc_kernel(pmd, vaddr);
118 if (!pte) 118 if (!pte)
119 return -ENOMEM; 119 return -ENOMEM;
120 if (map_pte_uncached(pte, orig_vaddr, end - vaddr, paddr_ptr)) 120 if (map_pte_uncached(pte, orig_vaddr, end - vaddr, paddr_ptr))
diff --git a/arch/parisc/mm/ioremap.c b/arch/parisc/mm/ioremap.c
index f2df502cdae3..5c7a1b3b9326 100644
--- a/arch/parisc/mm/ioremap.c
+++ b/arch/parisc/mm/ioremap.c
@@ -52,7 +52,7 @@ static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned lo
52 if (address >= end) 52 if (address >= end)
53 BUG(); 53 BUG();
54 do { 54 do {
55 pte_t * pte = pte_alloc_kernel(NULL, pmd, address); 55 pte_t * pte = pte_alloc_kernel(pmd, address);
56 if (!pte) 56 if (!pte)
57 return -ENOMEM; 57 return -ENOMEM;
58 remap_area_pte(pte, address, end - address, address + phys_addr, flags); 58 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
@@ -75,10 +75,9 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr,
75 flush_cache_all(); 75 flush_cache_all();
76 if (address >= end) 76 if (address >= end)
77 BUG(); 77 BUG();
78 spin_lock(&init_mm.page_table_lock);
79 do { 78 do {
80 pmd_t *pmd; 79 pmd_t *pmd;
81 pmd = pmd_alloc(dir, address); 80 pmd = pmd_alloc(&init_mm, dir, address);
82 error = -ENOMEM; 81 error = -ENOMEM;
83 if (!pmd) 82 if (!pmd)
84 break; 83 break;
@@ -89,7 +88,6 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr,
89 address = (address + PGDIR_SIZE) & PGDIR_MASK; 88 address = (address + PGDIR_SIZE) & PGDIR_MASK;
90 dir++; 89 dir++;
91 } while (address && (address < end)); 90 } while (address && (address < end));
92 spin_unlock(&init_mm.page_table_lock);
93 flush_tlb_all(); 91 flush_tlb_all();
94 return error; 92 return error;
95} 93}