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| author | Hugh Dickins <hugh@veritas.com> | 2005-10-30 02:16:21 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-30 05:40:40 +0100 |
| commit | 872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch) | |
| tree | 1dfc8b9f2754bdfff645188e497865c00201d535 /arch/arm26/mm | |
| parent | [PATCH] mm: ia64 use expand_upwards (diff) | |
| download | linux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.xz linux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.zip | |
[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/mm')
| -rw-r--r-- | arch/arm26/mm/memc.c | 3 |
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 |