Author: glebius
Date: Mon Dec 22 09:02:21 2014
New Revision: 276056
URL: https://svnweb.freebsd.org/changeset/base/276056
Log:
Add flag VM_ALLOC_NOWAIT for vm_page_grab() that prevents sleeping and
allows the function to fail.
Reviewed by: kib, alc
Sponsored by: Nginx, Inc.
Modified:
head/sys/vm/vm_page.c
head/sys/vm/vm_page.h
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Mon Dec 22 09:00:47 2014 (r276055)
+++ head/sys/vm/vm_page.c Mon Dec 22 09:02:21 2014 (r276056)
@@ -2711,6 +2711,8 @@ retrylookup:
sleep = (allocflags & VM_ALLOC_IGN_SBUSY) != 0 ?
vm_page_xbusied(m) : vm_page_busied(m);
if (sleep) {
+ if ((allocflags & VM_ALLOC_NOWAIT) != 0)
+ return (NULL);
/*
* Reference the page before unlocking and
* sleeping so that the page daemon is less
@@ -2738,6 +2740,8 @@ retrylookup:
}
m = vm_page_alloc(object, pindex, allocflags);
if (m == NULL) {
+ if ((allocflags & VM_ALLOC_NOWAIT) != 0)
+ return (NULL);
VM_OBJECT_WUNLOCK(object);
VM_WAIT;
VM_OBJECT_WLOCK(object);
Modified: head/sys/vm/vm_page.h
==============================================================================
--- head/sys/vm/vm_page.h Mon Dec 22 09:00:47 2014 (r276055)
+++ head/sys/vm/vm_page.h Mon Dec 22 09:02:21 2014 (r276056)
@@ -405,6 +405,7 @@ vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa)
#define VM_ALLOC_IGN_SBUSY 0x1000 /* (g) Ignore shared busy flag
*/
#define VM_ALLOC_NODUMP 0x2000 /* (ag) don't include in dump */
#define VM_ALLOC_SBUSY 0x4000 /* (acg) Shared busy the page */
+#define VM_ALLOC_NOWAIT 0x8000 /* (g) Do not sleep, return
NULL */
#define VM_ALLOC_COUNT_SHIFT 16
#define VM_ALLOC_COUNT(count) ((count) << VM_ALLOC_COUNT_SHIFT)
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