Author: alc
Date: Mon May 23 16:59:05 2016
New Revision: 300522
URL: https://svnweb.freebsd.org/changeset/base/300522
Log:
Correct an error in a comment: One of the conditions for page allocation
is actually the opposite of that stated in the comment.
Remove an unnecessary assignment. Use an assertion to document the fact
that no assignment is needed.
Rewrite another comment to clarify that the page is not completely valid.
Reviewed by: kib
Modified:
head/sys/vm/vm_fault.c
Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c Mon May 23 16:49:26 2016 (r300521)
+++ head/sys/vm/vm_fault.c Mon May 23 16:59:05 2016 (r300522)
@@ -496,11 +496,13 @@ fast_failed:
goto readrest;
break;
}
+ KASSERT(fs.m == NULL, ("fs.m should be NULL, not %p", fs.m));
/*
- * Page is not resident. If this is the search termination
- * or the pager might contain the page, allocate a new page.
- * Default objects are zero-fill, there is no real pager.
+ * Page is not resident. If the pager might contain the page
+ * or this is the beginning of the search, allocate a new
+ * page. (Default objects are zero-fill, so there is no real
+ * pager for them.)
*/
if (fs.object->type != OBJT_DEFAULT ||
fs.object == fs.first_object) {
@@ -517,7 +519,6 @@ fast_failed:
* there, and allocation can fail, causing
* restart and new reading of the p_flag.
*/
- fs.m = NULL;
if (!vm_page_count_severe() || P_KILLED(curproc)) {
#if VM_NRESERVLEVEL > 0
vm_object_color(fs.object, atop(vaddr) -
@@ -541,14 +542,12 @@ fast_failed:
readrest:
/*
- * We have found a valid page or we have allocated a new page.
- * The page thus may not be valid or may not be entirely
- * valid.
+ * We have either allocated a new page or found an existing
+ * page that is only partially valid.
*
* Attempt to fault-in the page if there is a chance that the
* pager has it, and potentially fault in additional pages
- * at the same time. For default objects simply provide
- * zero-filled pages.
+ * at the same time.
*/
if (fs.object->type != OBJT_DEFAULT) {
int rv;
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