diff options
| author | Hugh Dickins <hugh@veritas.com> | 2005-10-30 04:16:21 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-30 07:40:40 +0300 |
| commit | 872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch) | |
| tree | 1dfc8b9f2754bdfff645188e497865c00201d535 /arch/x86_64 | |
| 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/x86_64')
| -rw-r--r-- | arch/x86_64/mm/ioremap.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/x86_64/mm/ioremap.c b/arch/x86_64/mm/ioremap.c index 6972df480d2b..ecf7acb5db9b 100644 --- a/arch/x86_64/mm/ioremap.c +++ b/arch/x86_64/mm/ioremap.c @@ -60,7 +60,7 @@ static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned lo if (address >= end) BUG(); do { - pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address); + pte_t * pte = pte_alloc_kernel(pmd, address); if (!pte) return -ENOMEM; remap_area_pte(pte, address, end - address, address + phys_addr, flags); @@ -105,7 +105,6 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr, flush_cache_all(); if (address >= end) BUG(); - spin_lock(&init_mm.page_table_lock); do { pud_t *pud; pud = pud_alloc(&init_mm, pgd, address); @@ -119,7 +118,6 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr, address = (address + PGDIR_SIZE) & PGDIR_MASK; pgd++; } while (address && (address < end)); - spin_unlock(&init_mm.page_table_lock); flush_tlb_all(); return error; } |