Commit 3e1f0645 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mempolicy: disallow static or relative flags for local preferred mode 



MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES don't mean anything for
MPOL_PREFERRED policies that were created with an empty nodemask (for purely
local allocations).  They'll never be invalidated because the allowed mems of
a task changes or need to be rebound relative to a cpuset's placement.

Also fixes a bug identified by Lee Schermerhorn that disallowed empty
nodemasks to be passed to MPOL_PREFERRED to specify local allocations.  [A
different, somewhat incomplete, patch already existed in 25-rc5-mm1.]

Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3842b46d

Documentation/vm/numa_memory_policy.txt

+14 −2
Original line number Diff line number Diff line
@@ -205,6 +205,12 @@ Components of Memory Policies 
	    local allocation for a specific range of addresses--i.e. for

	    VMA policies.



	    It is possible for the user to specify that local allocation is

	    always preferred by passing an empty nodemask with this mode.

	    If an empty nodemask is passed, the policy cannot use the

	    MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES flags described

	    below.



	MPOL_INTERLEAVED:  This mode specifies that page allocations be

	interleaved, on a page granularity, across the nodes specified in

	the policy.  This mode also behaves slightly differently, based on
@@ -254,7 +260,10 @@ Components of Memory Policies 
	    occurs over that node.  If no nodes from the user's nodemask are

	    now allowed, the Default behavior is used.



	    MPOL_F_STATIC_NODES cannot be used with MPOL_F_RELATIVE_NODES.

	    MPOL_F_STATIC_NODES cannot be combined with the

	    MPOL_F_RELATIVE_NODES flag.  It also cannot be used for

	    MPOL_PREFERRED policies that were created with an empty nodemask

	    (local allocation).



	MPOL_F_RELATIVE_NODES:  This flag specifies that the nodemask passed

	by the user will be mapped relative to the set of the task or VMA's
@@ -301,7 +310,10 @@ Components of Memory Policies 
	    set of memory nodes allowed by the task's cpuset, as that may

	    change over time.



	    MPOL_F_RELATIVE_NODES cannot be used with MPOL_F_STATIC_NODES.

	    MPOL_F_RELATIVE_NODES cannot be combined with the

	    MPOL_F_STATIC_NODES flag.  It also cannot be used for

	    MPOL_PREFERRED policies that were created with an empty nodemask

	    (local allocation).



MEMORY POLICY APIs

mm/mempolicy.c

+26 −16
Original line number Diff line number Diff line
@@ -181,27 +181,43 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, 
{

	struct mempolicy *policy;

	nodemask_t cpuset_context_nmask;

	int localalloc = 0;

	int ret;



	pr_debug("setting mode %d flags %d nodes[0] %lx\n",

		 mode, flags, nodes ? nodes_addr(*nodes)[0] : -1);



	if (mode == MPOL_DEFAULT)

	if (mode == MPOL_DEFAULT) {

		if (nodes && !nodes_empty(*nodes))

			return ERR_PTR(-EINVAL);

		return NULL;

	if (!nodes || nodes_empty(*nodes)) {

		if (mode != MPOL_PREFERRED)

	}

	VM_BUG_ON(!nodes);



	/*

	 * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or

	 * MPOL_F_RELATIVE_NODES if the nodemask is empty (local allocation).

	 * All other modes require a valid pointer to a non-empty nodemask.

	 */

	if (mode == MPOL_PREFERRED) {

		if (nodes_empty(*nodes)) {

			if (((flags & MPOL_F_STATIC_NODES) ||

			     (flags & MPOL_F_RELATIVE_NODES)))

				return ERR_PTR(-EINVAL);

		localalloc = 1;	/* special case:  no mode flags */

			nodes = NULL;	/* flag local alloc */

		}

	} else if (nodes_empty(*nodes))

		return ERR_PTR(-EINVAL);

	policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);

	if (!policy)

		return ERR_PTR(-ENOMEM);

	atomic_set(&policy->refcnt, 1);

	policy->policy = mode;



	if (!localalloc) {

	policy->flags = flags;



	if (nodes) {

		/*

		 * cpuset related setup doesn't apply to local allocation

		 */

		cpuset_update_task_memory_state();

		if (flags & MPOL_F_RELATIVE_NODES)

			mpol_relative_nodemask(&cpuset_context_nmask, nodes,
@@ -217,7 +233,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, 
	}



	ret = mpol_ops[mode].create(policy,

				localalloc ? NULL : &cpuset_context_nmask);

				nodes ? &cpuset_context_nmask : NULL);

	if (ret < 0) {

		kmem_cache_free(policy_cache, policy);

		return ERR_PTR(ret);
@@ -259,10 +275,6 @@ static void mpol_rebind_preferred(struct mempolicy *pol, 
{

	nodemask_t tmp;



	/*

	 * check 'STATIC_NODES first, as preferred_node == -1 may be

	 * a temporary, "fallback" state for this policy.

	 */

	if (pol->flags & MPOL_F_STATIC_NODES) {

		int node = first_node(pol->w.user_nodemask);
@@ -270,12 +282,10 @@ static void mpol_rebind_preferred(struct mempolicy *pol, 
			pol->v.preferred_node = node;

		else

			pol->v.preferred_node = -1;

	} else if (pol->v.preferred_node == -1) {

		return;	/* no remap required for explicit local alloc */

	} else if (pol->flags & MPOL_F_RELATIVE_NODES) {

		mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);

		pol->v.preferred_node = first_node(tmp);

	} else {

	} else if (pol->v.preferred_node != -1) {

		pol->v.preferred_node = node_remap(pol->v.preferred_node,

						   pol->w.cpuset_mems_allowed,

						   *nodes);

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