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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/arm26
parent46dea3d092d23a58b42499cc8a21de0fad079f4a (diff)
downloadlinux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.bz2
[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/arm26')
-rw-r--r--arch/arm26/mm/memc.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm26/mm/memc.c b/arch/arm26/mm/memc.c
index 8e8a2bb2487d..d6b008b8db76 100644
--- a/arch/arm26/mm/memc.c
+++ b/arch/arm26/mm/memc.c
@@ -92,7 +92,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
if (!new_pmd)
goto no_pmd;
- new_pte = pte_alloc_kernel(mm, new_pmd, 0);
+ new_pte = pte_alloc_map(mm, new_pmd, 0);
if (!new_pte)
goto no_pte;
@@ -101,6 +101,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
init_pte = pte_offset(init_pmd, 0);
set_pte(new_pte, *init_pte);
+ pte_unmap(new_pte);
/*
* the page table entries are zeroed