Changeset 60372 in vbox

Timestamp:

Apr 7, 2016 2:12:17 PM (9 years ago)

Author:

vboxsync

Message:

Runtime/r0drv/linux: bugref:8315: don't set the PG_reserved flag on potential compound pages. Play safe and do this change only on Linux 4.5 and later which would panic in that case (forward-port of r106453)

Location:

trunk

Files:

• . (modified) (1 prop)
• src/VBox (modified) (1 prop)
• src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c (modified) (2 diffs)

trunk/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c

@@ -373 +373 @@
     pMemLnx->fContiguous = fContiguous;
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
     /*
      * Reserve the pages.
+     * 
+     * Linux >= 4.5 with CONFIG_DEBUG_VM panics when setting PG_reserved on compound
+     * pages. According to Michal Hocko this shouldn't be necessary anyway because
+     * as pages which are not on the LRU list are never evictable.
      */
     for (iPage = 0; iPage < cPages; iPage++)
         SetPageReserved(pMemLnx->apPages[iPage]);
+#endif
 
     /*
@@ -424 +430 @@
         while (iPage-- > 0)
         {
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
+            /*
+             * See SetPageReserved() in rtR0MemObjLinuxAllocPages()
+             */
             ClearPageReserved(pMemLnx->apPages[iPage]);
+#endif
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 4, 22)
 #else