Redo the page table page allocation on MIPS, as suggested by

alc@.

The UMA zone based allocation is replaced by a scheme that creates
a new free page list for the KSEG0 region, and a new function
in sys/vm that allocates pages from a specific free page list.

This also fixes a race condition introduced by the UMA based page table
page allocation code. Dropping the page queue and pmap locks before
the call to uma_zfree, and re-acquiring them afterwards  will introduce
a race condtion(noted by alc@).

The changes are :
- Revert the earlier changes in MIPS pmap.c that added UMA zone for
page table pages.
- Add a new freelist VM_FREELIST_HIGHMEM to MIPS vmparam.h for memory that
is not directly mapped (in 32bit kernel). Normal page allocations will first
try the HIGHMEM freelist and then the default(direct mapped) freelist.
- Add a new function 'vm_page_t vm_page_alloc_freelist(int flind, int
order, int req)' to vm/vm_page.c to allocate a page from a specified
freelist. The MIPS page table pages will be allocated using this function
from the freelist containing direct mapped pages.
- Move the page initialization code from vm_phys_alloc_contig() to a
new function vm_page_alloc_init(), and use this function to initialize
pages in vm_page_alloc_freelist() too.
- Split the  function vm_phys_alloc_pages(int pool, int order) to create
vm_phys_alloc_freelist_pages(int flind, int pool, int order), and use
this function from both vm_page_alloc_freelist() and vm_phys_alloc_pages().

Reviewed by:	alc

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index a877c43..86119a1 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -262,6 +262,7 @@ extern struct vpglocks pa_lock[];
  *
  */
 
+struct vnode;
 extern int vm_page_zero_count;
 
 extern vm_page_t vm_page_array;		/* First resident page in table */
@@ -339,6 +340,8 @@ void vm_pageq_remove(vm_page_t m);
 
 void vm_page_activate (vm_page_t);
 vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
+vm_page_t vm_page_alloc_freelist(int, int, int);
+struct vnode *vm_page_alloc_init(vm_page_t);
 vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
 void vm_page_cache(vm_page_t);
 void vm_page_cache_free(vm_object_t, vm_pindex_t, vm_pindex_t);