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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/ppc64
parent46dea3d092d23a58b42499cc8a21de0fad079f4a (diff)
[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/ppc64')
-rw-r--r--arch/ppc64/mm/imalloc.c5
-rw-r--r--arch/ppc64/mm/init.c4
2 files changed, 1 insertions, 8 deletions
diff --git a/arch/ppc64/mm/imalloc.c b/arch/ppc64/mm/imalloc.c
index c65b87b9275..f4ca29cf536 100644
--- a/arch/ppc64/mm/imalloc.c
+++ b/arch/ppc64/mm/imalloc.c
@@ -300,12 +300,7 @@ void im_free(void * addr)
for (p = &imlist ; (tmp = *p) ; p = &tmp->next) {
if (tmp->addr == addr) {
*p = tmp->next;
-
- /* XXX: do we need the lock? */
- spin_lock(&init_mm.page_table_lock);
unmap_vm_area(tmp);
- spin_unlock(&init_mm.page_table_lock);
-
kfree(tmp);
up(&imlist_sem);
return;
diff --git a/arch/ppc64/mm/init.c b/arch/ppc64/mm/init.c
index be64b157afc..a45584b3440 100644
--- a/arch/ppc64/mm/init.c
+++ b/arch/ppc64/mm/init.c
@@ -155,7 +155,6 @@ static int map_io_page(unsigned long ea, unsigned long pa, int flags)
unsigned long vsid;
if (mem_init_done) {
- spin_lock(&init_mm.page_table_lock);
pgdp = pgd_offset_k(ea);
pudp = pud_alloc(&init_mm, pgdp, ea);
if (!pudp)
@@ -163,12 +162,11 @@ static int map_io_page(unsigned long ea, unsigned long pa, int flags)
pmdp = pmd_alloc(&init_mm, pudp, ea);
if (!pmdp)
return -ENOMEM;
- ptep = pte_alloc_kernel(&init_mm, pmdp, ea);
+ ptep = pte_alloc_kernel(pmdp, ea);
if (!ptep)
return -ENOMEM;
set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
__pgprot(flags)));
- spin_unlock(&init_mm.page_table_lock);
} else {
unsigned long va, vpn, hash, hpteg;