Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -1270,11 +1270,19 @@
 ** opened.  Any outstanding pages are invalidated and subsequent attempts
 ** to access those pages will likely result in a coredump.
 */
 static void pager_reset(Pager *pPager){
   PgHdr *pPg, *pNext;
+#ifndef SQLITE_MUTEX_NOOP
+  sqlite3_mutex *mutex;
+#endif
   if( pPager->errCode ) return;
+#ifndef SQLITE_MUTEX_NOOP
+  mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM2);
+  sqlite3_mutex_enter(mutex);
+#endif
+
   for(pPg=pPager->pAll; pPg; pPg=pNext){
     IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno));
     PAGER_INCR(sqlite3_pager_pgfree_count);
     pNext = pPg->pNextAll;
     lruListRemove(pPg);
@@ -1290,10 +1298,11 @@
   pPager->nHash = 0;
   sqlite3_free(pPager->aHash);
   pPager->nPage = 0;
   pPager->aHash = 0;
   pPager->nRef = 0;
+  sqlite3_mutex_leave(mutex);
 }
 
 /*
 ** Unlock the database file. 
 **
@@ -2634,10 +2643,15 @@
 */
 static void pager_truncate_cache(Pager *pPager){
   PgHdr *pPg;
   PgHdr **ppPg;
   int dbSize = pPager->dbSize;
+#ifndef SQLITE_MUTEX_NOOP
+  sqlite3_mutex *mutex;
+  mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM2);
+#endif
+  sqlite3_mutex_enter(mutex);
 
   ppPg = &pPager->pAll;
   while( (pPg = *ppPg)!=0 ){
     if( pPg->pgno<=dbSize ){
       ppPg = &pPg->pNextAll;
@@ -2653,10 +2667,11 @@
       sqlite3_free(pPg->pData);
       sqlite3_free(pPg);
       pPager->nPage--;
     }
   }
+  sqlite3_mutex_leave(mutex);
 }
 
 /*
 ** Try to obtain a lock on a file.  Invoke the busy callback if the lock
 ** is currently not available.  Repeat until the busy callback returns