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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/frv/mm/dma-alloc.c
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/frv/mm/dma-alloc.c')
-rw-r--r--arch/frv/mm/dma-alloc.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/frv/mm/dma-alloc.c b/arch/frv/mm/dma-alloc.c
index cfc4f97490c6..342823aad758 100644
--- a/arch/frv/mm/dma-alloc.c
+++ b/arch/frv/mm/dma-alloc.c
@@ -55,21 +55,18 @@ static int map_page(unsigned long va, unsigned long pa, pgprot_t prot)
55 pte_t *pte; 55 pte_t *pte;
56 int err = -ENOMEM; 56 int err = -ENOMEM;
57 57
58 spin_lock(&init_mm.page_table_lock);
59
60 /* Use upper 10 bits of VA to index the first level map */ 58 /* Use upper 10 bits of VA to index the first level map */
61 pge = pgd_offset_k(va); 59 pge = pgd_offset_k(va);
62 pue = pud_offset(pge, va); 60 pue = pud_offset(pge, va);
63 pme = pmd_offset(pue, va); 61 pme = pmd_offset(pue, va);
64 62
65 /* Use middle 10 bits of VA to index the second-level map */ 63 /* Use middle 10 bits of VA to index the second-level map */
66 pte = pte_alloc_kernel(&init_mm, pme, va); 64 pte = pte_alloc_kernel(pme, va);
67 if (pte != 0) { 65 if (pte != 0) {
68 err = 0; 66 err = 0;
69 set_pte(pte, mk_pte_phys(pa & PAGE_MASK, prot)); 67 set_pte(pte, mk_pte_phys(pa & PAGE_MASK, prot));
70 } 68 }
71 69
72 spin_unlock(&init_mm.page_table_lock);
73 return err; 70 return err;
74} 71}
75 72