From 3e1f064562fcff7bf3856bc1d00dfa84d4f121cc Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 28 Apr 2008 02:12:34 -0700 Subject: 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 Cc: Christoph Lameter Cc: Lee Schermerhorn Cc: Andi Kleen Cc: Randy Dunlap Signed-off-by: Lee Schermerhorn Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/vm/numa_memory_policy.txt | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'Documentation/vm/numa_memory_policy.txt') diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt index 706410dfb9e5..1c7dd21623d2 100644 --- a/Documentation/vm/numa_memory_policy.txt +++ b/Documentation/vm/numa_memory_policy.txt @@ -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 -- cgit v1.2.2