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Fix a bug that has annoyed me for a long time. In pmap_enter(), if 

there are no pages available immediately to use as a PT page, don't
just roll over and die.  Only do that if we're the kernel pmap (shouldn't
happen very ofter [ever?!], and I'm not certain we're guaranteed valid
thread context when operating on the kernel pmap).  For user pmaps, wait
for the pagedaemon to wake us up when more free pages are available.
This commit is contained in:
thorpej 1999-01-26 09:03:31 +00:00
parent 6c30816c15
commit 8851ed323e
1 changed files with 31 additions and 6 deletions
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37
sys/arch/arm32/arm32/pmap.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.39 1999/01/17 06:58:16 mark Exp $ */
/* $NetBSD: pmap.c,v 1.40 1999/01/26 09:03:31 thorpej Exp $ */
/*
* Copyright (c) 1994-1998 Mark Brinicombe.
@ -2057,14 +2057,39 @@ pmap_enter(pmap, va, pa, prot, wired)
vm_offset_t l2pa;
/* Allocate a page table */
for (;;) {
#if defined(UVM)
page = uvm_pagealloc(NULL, 0, NULL);
page = uvm_pagealloc(NULL, 0, NULL);
#else
page = vm_page_alloc1();
page = vm_page_alloc1();
#endif
/* XXX should try and free up memory if alloc fails */
if (page == NULL)
panic("pmap_enter: No more physical pages\n");
if (page != NULL)
break;
/*
* No page available. If we're the kernel
* pmap, we die, since we might not have
* a valid thread context. For user pmaps,
* we assume that we _do_ have a valid thread
* context, so we wait here for the pagedaemon
* to free up some pages.
*
* XXX THE VM CODE IS PROBABLY HOLDING LOCKS
* XXX RIGHT NOW, BUT ONLY ON OUR PARENT VM_MAP
* XXX SO THIS IS PROBABLY SAFE. In any case,
* XXX other pmap modules claim it is safe to
* XXX sleep here if it's a user pmap.
*/
if (pmap == pmap_kernel())
panic("pmap_enter: kernel pmap and no more free pages");
else {
#if defined(UVM)
uvm_wait("pmap_enter");
#else
vm_wait("pmap_enter");
#endif
}
}
/* Wire this page table into the L1 */
l2pa = VM_PAGE_TO_PHYS(page);