linux/arch/cris
Hugh Dickins 872fec16d9 [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>
2005-10-29 21:40:40 -07:00
..
arch-v10 kbuild: cris use generic asm-offsets.h support 2005-09-09 22:44:31 +02:00
arch-v32 [NETFILTER]: Fix OOPSes on machines with discontiguous cpu numbering. 2005-10-13 14:41:23 -07:00
kernel [PATCH] NTP: ntp-helper functions 2005-09-07 16:57:34 -07:00
mm [PATCH] mm: init_mm without ptlock 2005-10-29 21:40:40 -07:00
defconfig [PATCH] CRIS update: configuration and build 2005-07-27 16:25:59 -07:00
Kconfig [NET]: add a top-level Networking menu to *config 2005-07-11 21:03:49 -07:00
Kconfig.debug [PATCH] arch/cris/Kconfig.debug: use lib/Kconfig.debug 2005-09-05 00:06:19 -07:00
Makefile kbuild: rename prepare to archprepare to fix dependency chain 2005-09-11 22:30:22 +02:00