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Date:      Wed, 20 Feb 2019 22:41:14 +0000 (UTC)
From:      Andrew Turner <andrew@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r344391 - head/sys/kern
Message-ID:  <201902202241.x1KMfEpZ055514@repo.freebsd.org>
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Author: andrew
Date: Wed Feb 20 22:41:14 2019
New Revision: 344391
URL: https://svnweb.freebsd.org/changeset/base/344391

Log:
  Unwire the kcov buffer when freeing the info struct.
  
  Without this the physical memory will not be returned to the kernel.
  
  While here call vm_object_reference on the object when mmapping the buffer.
  This removed the need for buggy tracking of if it has been mapped or not.
  
  This fixes issues where kcov could use all the system memory.
  
  Reported by:	tuexen
  Reviewed by:	kib
  Sponsored by:	DARPA, AFTL
  Differential Revision:	https://reviews.freebsd.org/D19252

Modified:
  head/sys/kern/kern_kcov.c

Modified: head/sys/kern/kern_kcov.c
==============================================================================
--- head/sys/kern/kern_kcov.c	Wed Feb 20 22:32:28 2019	(r344390)
+++ head/sys/kern/kern_kcov.c	Wed Feb 20 22:41:14 2019	(r344391)
@@ -58,6 +58,7 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_object.h>
 #include <vm/vm_page.h>
 #include <vm/vm_pager.h>
+#include <vm/vm_param.h>
 
 MALLOC_DEFINE(M_KCOV_INFO, "kcovinfo", "KCOV info type");
 
@@ -347,6 +348,7 @@ kcov_mmap_single(struct cdev *dev, vm_ooffset_t *offse
 	    info->mmap != false)
 		return (EINVAL);
 
+	vm_object_reference(info->bufobj);
 	info->mmap = true;
 	*offset = 0;
 	*object = info->bufobj;
@@ -393,13 +395,26 @@ kcov_alloc(struct kcov_info *info, size_t entries)
 static void
 kcov_free(struct kcov_info *info)
 {
+	vm_page_t m;
+	size_t i;
 
 	if (info->kvaddr != 0) {
 		pmap_qremove(info->kvaddr, info->bufsize / PAGE_SIZE);
 		kva_free(info->kvaddr, info->bufsize);
 	}
-	if (info->bufobj != NULL && !info->mmap)
+	if (info->bufobj != NULL) {
+		VM_OBJECT_WLOCK(info->bufobj);
+		m = vm_page_lookup(info->bufobj, 0);
+		for (i = 0; i < info->bufsize / PAGE_SIZE; i++) {
+			vm_page_lock(m);
+			vm_page_unwire_noq(m);
+			vm_page_unlock(m);
+
+			m = vm_page_next(m);
+		}
+		VM_OBJECT_WUNLOCK(info->bufobj);
 		vm_object_deallocate(info->bufobj);
+	}
 	free(info, M_KCOV_INFO);
 }

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