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, 1 insertions, 0 deletions

diff --git a/sys/vm/vm_phys.h b/sys/vm/vm_phys.h
index 0e012c3..0dbd96a 100644
--- a/sys/vm/vm_phys.h
+++ b/sys/vm/vm_phys.h
@@ -44,6 +44,7 @@ void vm_phys_add_page(vm_paddr_t pa);
 vm_page_t vm_phys_alloc_contig(unsigned long npages,
     vm_paddr_t low, vm_paddr_t high,
     unsigned long alignment, unsigned long boundary);
+vm_page_t vm_phys_alloc_freelist_pages(int flind, int pool, int order);
 vm_page_t vm_phys_alloc_pages(int pool, int order);
 vm_paddr_t vm_phys_bootstrap_alloc(vm_size_t size, unsigned long alignment);
 void vm_phys_free_pages(vm_page_t m, int order);