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| author | Hugh Dickins <hugh@veritas.com> | 2005-10-29 18:16:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-29 21:40:40 -0700 |
| commit | 872fec16d9a0ed3b75b8893aa217e49cca575ee5 (patch) | |
| tree | 1dfc8b9f2754bdfff645188e497865c00201d535 /arch/alpha/mm | |
| parent | 46dea3d092d23a58b42499cc8a21de0fad079f4a (diff) | |
| download | linux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.gz linux-872fec16d9a0ed3b75b8893aa217e49cca575ee5.tar.bz2 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/alpha/mm')
| -rw-r--r-- | arch/alpha/mm/remap.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/arch/alpha/mm/remap.c b/arch/alpha/mm/remap.c index 19817ad3d89b..a78356c3ead5 100644 --- a/arch/alpha/mm/remap.c +++ b/arch/alpha/mm/remap.c @@ -2,7 +2,6 @@ #include <asm/pgalloc.h> #include <asm/cacheflush.h> -/* called with the page_table_lock held */ static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size, unsigned long phys_addr, unsigned long flags) @@ -31,7 +30,6 @@ remap_area_pte(pte_t * pte, unsigned long address, unsigned long size, } while (address && (address < end)); } -/* called with the page_table_lock held */ static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size, unsigned long phys_addr, unsigned long flags) @@ -46,7 +44,7 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size, 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, @@ -70,7 +68,6 @@ __alpha_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 { pmd_t *pmd; pmd = pmd_alloc(&init_mm, dir, address); @@ -84,7 +81,6 @@ __alpha_remap_area_pages(unsigned long address, unsigned long phys_addr, address = (address + PGDIR_SIZE) & PGDIR_MASK; dir++; } while (address && (address < end)); - spin_unlock(&init_mm.page_table_lock); return error; } |