Messages in this thread Patch in this message | | | Date | Fri, 7 Mar 2008 17:24:15 -0800 (PST) | From | David Rientjes <> | Subject | [patch -mm 1/2] mempolicy: disallow static or relative flags for local preferred mode |
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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.
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: David Rientjes <rientjes@google.com> --- Documentation/vm/numa_memory_policy.txt | 16 ++++++++++++++-- mm/mempolicy.c | 17 ++++++++++++----- 2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt --- a/Documentation/vm/numa_memory_policy.txt +++ b/Documentation/vm/numa_memory_policy.txt @@ -210,6 +210,12 @@ 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 @@ -259,7 +265,10 @@ 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 @@ -306,7 +315,10 @@ 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 diff --git a/mm/mempolicy.c b/mm/mempolicy.c --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -151,9 +151,7 @@ static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes) static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes) { - if (nodes_empty(*nodes)) - return -EINVAL; - pol->v.preferred_node = first_node(*nodes); + pol->v.preferred_node = !nodes_empty(*nodes) ? first_node(*nodes) : -1; return 0; } @@ -176,7 +174,16 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, pr_debug("setting mode %d flags %d nodes[0] %lx\n", mode, flags, nodes ? nodes_addr(*nodes)[0] : -1); - if (nodes && nodes_empty(*nodes) && mode != MPOL_PREFERRED) + /* + * 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) && ((flags & MPOL_F_STATIC_NODES) || + (flags & MPOL_F_RELATIVE_NODES))) + return ERR_PTR(-EINVAL); + } else if (nodes && nodes_empty(*nodes)) return ERR_PTR(-EINVAL); if (mode == MPOL_DEFAULT) return NULL; @@ -250,7 +257,7 @@ static void mpol_rebind_preferred(struct mempolicy *pol, } 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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