Re: CVS commit: src/sys/uvm

[Jason R Thorpe <thorpej%wasabisystems.com@localhost>]

On Tue, Mar 04, 2003 at 04:43:37PM +0900, enami tsugutomo wrote:

 > I'm afraid null pointer is dereferenced when accessing something like
 > uobj->pgops->pgo_put (we test if pgo_put is null or not, but doesn't
 > test if pgops is null).

Ok, I think the easiest thing to do is just make sure the page
never ends up on a paging queue.  I'll check in the following
patch.

-- 
        -- Jason R. Thorpe <thorpej%wasabisystems.com@localhost>

Index: uvm_loan.c
===================================================================
RCS file: /cvsroot/src/sys/uvm/uvm_loan.c,v
retrieving revision 1.40
diff -c -r1.40 uvm_loan.c
*** uvm_loan.c  2003/03/04 06:18:54     1.40
--- uvm_loan.c  2003/03/05 01:01:18
***************
*** 671,676 ****
--- 671,684 ----
                pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
                pg->flags |= PG_RDONLY;
                UVM_PAGE_OWN(pg, NULL);
+ 
+               /*
+                * we never want this page to be on a paging queue,
+                * so wire it.
+                */
+               uvm_lock_pageq();
+               uvm_pagewire(pg);
+               uvm_unlock_pageq();
        }
  
        if ((flags & UVM_LOAN_TOANON) == 0) {   /* loaning to kernel-page */
***************
*** 715,721 ****
        pg->uanon = anon;
        uvm_lock_pageq();
        pg->loan_count++;
-       uvm_pageactivate(pg);
        uvm_unlock_pageq();
        simple_unlock(&uvm_loanzero_object.vmobjlock);
        **output = anon;
--- 723,728 ----