PATCH 1/2 cpusetmm-update-tasks-mems_allowed-in-time-fix
Against: 2.6.30-rc3-mmotm-090424-1814
The rework of mpol_new() to extract the adjusting of the node mask
to apply cpuset and mpol flags "context" breaks set_mempolicy() and
mbind() with MPOL_PREFERRED and a NULL nodemask--i.e., explicit local
allocation. Fix this by adding the check for MPOL_PREFERRED and
empty node mask to mpol_new_mpolicy().
Remove the now unneeded 'nodes = NULL' from mpol_new().
Note that mpol_new_mempolicy() is always called with a non-NULL
'nodes' parameter now that it has been removed from mpol_new().
Therefore, we don't need to test nodes for NULL before testing
it for 'empty'. However, just to be extra paranoid, add a
VM_BUG_ON() to verify this assumption.
Tested on x86_64 with numactl-2.0.3-rc2+ regression test.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
mm/mempolicy.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
Index: linux-2.6.30-rc3-mmotm-090424-1814/mm/mempolicy.c
===================================================================
--- linux-2.6.30-rc3-mmotm-090424-1814.orig/mm/mempolicy.c 2009-04-27 13:42:53.000000000 -0400
+++ linux-2.6.30-rc3-mmotm-090424-1814/mm/mempolicy.c 2009-04-28 13:32:32.000000000 -0400
@@ -182,8 +182,9 @@ static int mpol_new_bind(struct mempolic
return 0;
}
/*
- * This function is called after mpol_new(). The parameter -- nodes needn't
- * been check because mpol_new() has done it. Maybe this implement is ugly.
+ * This function is called after mpol_new(). mpol_new() has already validated
+ * the nodes parameter with respect to the policy mode and flags. But, we
+ * need to handle an empty nodemaks with MPOL_PREFERRED here.
*
* We use task's alloc_lock to protect task's mems_allowed and mempolicy.
* so this function should be called with task's alloc_lock held.
@@ -197,7 +198,10 @@ static int mpol_new_mempolicy(struct mem
if (pol == NULL)
return 0;
- if (nodes) {
+ VM_BUG_ON(!nodes);
+ if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes))
+ nodes = NULL; /* explicit local allocation */
+ else {
if (pol->flags & MPOL_F_RELATIVE_NODES)
mpol_relative_nodemask(&cpuset_context_nmask, nodes,
&cpuset_current_mems_allowed);
@@ -243,7 +247,6 @@ static struct mempolicy *mpol_new(unsign
if (((flags & MPOL_F_STATIC_NODES) ||
(flags & MPOL_F_RELATIVE_NODES)))
return ERR_PTR(-EINVAL);
- nodes = NULL; /* flag local alloc */
}
} else if (nodes_empty(*nodes))
return ERR_PTR(-EINVAL);
--
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