linux/arch/s390
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
..
appldata [PATCH] s390: fix inline assembly in appldata 2005-07-29 15:01:15 -07:00
boot [PATCH] use ${CROSS_COMPILE}installkernel in arch/*/boot/install.sh 2005-06-23 09:45:07 -07:00
crypto Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
kernel [PATCH] s390 signal annotations 2005-09-29 08:46:27 -07:00
lib [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
math-emu Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mm [PATCH] mm: init_mm without ptlock 2005-10-29 21:40:40 -07:00
oprofile Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
defconfig [PATCH] s390: default configuration 2005-09-17 11:49:58 -07:00
Kconfig [NET]: add a top-level Networking menu to *config 2005-07-11 21:03:49 -07:00
Kconfig.debug Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Makefile Merge master.kernel.org:/pub/scm/linux/kernel/git/sam/kbuild 2005-09-09 15:46:49 -07:00