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author | Hugh Dickins <hugh@veritas.com> | 2005-10-30 01:16:21 (GMT) |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-30 04:40:40 (GMT) |
commit | 872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch) | |
tree | 1dfc8b9f2754bdfff645188e497865c00201d535 /arch/frv/mm | |
parent | 46dea3d092d23a58b42499cc8a21de0fad079f4a (diff) | |
download | linux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.xz |
[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')
-rw-r--r-- | arch/frv/mm/dma-alloc.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/frv/mm/dma-alloc.c b/arch/frv/mm/dma-alloc.c index cfc4f97..342823a 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) pte_t *pte; int err = -ENOMEM; - spin_lock(&init_mm.page_table_lock); - /* Use upper 10 bits of VA to index the first level map */ pge = pgd_offset_k(va); pue = pud_offset(pge, va); pme = pmd_offset(pue, va); /* Use middle 10 bits of VA to index the second-level map */ - pte = pte_alloc_kernel(&init_mm, pme, va); + pte = pte_alloc_kernel(pme, va); if (pte != 0) { err = 0; set_pte(pte, mk_pte_phys(pa & PAGE_MASK, prot)); } - spin_unlock(&init_mm.page_table_lock); return err; } |