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ubc_alloc: break loans on UBC_FAULTBUSY. 

it's necessary after recent file overwrite changes.
(http://mail-index.NetBSD.org/source-changes/2007/06/05/0014.html)
it should fix the problem reported by Sarton O'Brien on
current-users@/port-xen@.
(http://mail-index.NetBSD.org/current-users/2007/06/22/0001.html)
This commit is contained in:
yamt 2007-06-22 15:15:48 +00:00
parent 60f2903e7a
commit 670c065b9a
1 changed files with 24 additions and 4 deletions
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28
sys/uvm/uvm_bio.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: uvm_bio.c,v 1.58 2007/06/05 12:31:35 yamt Exp $ */
/* $NetBSD: uvm_bio.c,v 1.59 2007/06/22 15:15:48 yamt Exp $ */
/*
* Copyright (c) 1998 Chuck Silvers.
@ -34,7 +34,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.58 2007/06/05 12:31:35 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.59 2007/06/22 15:15:48 yamt Exp $");
#include "opt_uvmhist.h"
#include "opt_ubc.h"
@ -520,6 +520,7 @@ again:
umap->flags &= ~UMAP_MAPPING_CACHED;
pmap_remove(pmap_kernel(), va, va + ubc_winsize);
}
again_faultbusy:
memset(pgs, 0, sizeof(pgs));
simple_lock(&uobj->vmobjlock);
error = (*uobj->pgops->pgo_get)(uobj, trunc_page(offset), pgs,
@ -529,9 +530,28 @@ again:
goto out;
}
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[i];
KASSERT(pg->uobject == uobj);
if (pg->loan_count != 0) {
simple_lock(&uobj->vmobjlock);
if (pg->loan_count != 0) {
pg = uvm_loanbreak(pg);
}
simple_unlock(&uobj->vmobjlock);
if (pg == NULL) {
pmap_kremove(va, ubc_winsize);
pmap_update(pmap_kernel());
simple_lock(&uobj->vmobjlock);
uvm_page_unbusy(pgs, npages);
simple_unlock(&uobj->vmobjlock);
uvm_wait("ubc_alloc");
goto again_faultbusy;
}
pgs[i] = pg;
}
pmap_kenter_pa(va + slot_offset + (i << PAGE_SHIFT),
VM_PAGE_TO_PHYS(pgs[i]),
VM_PROT_READ | VM_PROT_WRITE);
VM_PAGE_TO_PHYS(pg), VM_PROT_READ | VM_PROT_WRITE);
}
pmap_update(pmap_kernel());
umap->flags |= UMAP_PAGES_LOCKED;