Author: alc
Date: Thu May 19 19:27:33 2016
New Revision: 300225
URL: https://svnweb.freebsd.org/changeset/base/300225
Log:
Clean up the handling of errors from vm_pager_get_pages(). Mostly, this
cleanup consists of fixes to comments. However, there is one change to
code: Remove special-case handling of errors involving the kernel map.
We do not perform I/O on the kernel map, so there is no need for this
special case.
Reviewed by: kib (an earlier version)
Modified:
head/sys/vm/vm_fault.c
Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c Thu May 19 19:13:43 2016 (r300224)
+++ head/sys/vm/vm_fault.c Thu May 19 19:27:33 2016 (r300225)
@@ -657,48 +657,40 @@ vnode_locked:
hardfault++;
break; /* break to PAGE HAS BEEN FOUND */
}
- /*
- * Remove the bogus page (which does not exist at this
- * object/offset); before doing so, we must get back
- * our object lock to preserve our invariant.
- *
- * Also wake up any other process that may want to bring
- * in this page.
- *
- * If this is the top-level object, we must leave the
- * busy page to prevent another process from rushing
- * past us, and inserting the page in that object at
- * the same time that we are.
- */
if (rv == VM_PAGER_ERROR)
printf("vm_fault: pager read error, pid %d
(%s)\n",
curproc->p_pid, curproc->p_comm);
+
/*
- * Data outside the range of the pager or an I/O error
- */
- /*
- * XXX - the check for kernel_map is a kludge to work
- * around having the machine panic on a kernel space
- * fault w/ I/O error.
+ * If an I/O error occurred or the requested page was
+ * outside the range of the pager, clean up and return
+ * an error.
*/
- if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR))
||
- (rv == VM_PAGER_BAD)) {
+ if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
vm_page_lock(fs.m);
vm_page_free(fs.m);
vm_page_unlock(fs.m);
fs.m = NULL;
unlock_and_deallocate(&fs);
- return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE :
KERN_PROTECTION_FAILURE);
+ return (rv == VM_PAGER_ERROR ? KERN_FAILURE :
+ KERN_PROTECTION_FAILURE);
}
+
+ /*
+ * The requested page does not exist at this object/
+ * offset. Remove the invalid page from the object,
+ * waking up anyone waiting for it, and continue on to
+ * the next object. However, if this is the top-level
+ * object, we must leave the busy page in place to
+ * prevent another process from rushing past us, and
+ * inserting the page in that object at the same time
+ * that we are.
+ */
if (fs.object != fs.first_object) {
vm_page_lock(fs.m);
vm_page_free(fs.m);
vm_page_unlock(fs.m);
fs.m = NULL;
- /*
- * XXX - we cannot just fall out at this
- * point, m has been freed and is invalid!
- */
}
}
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