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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.  [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: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes
2008-04-28 02:12:34 -07:00
committed by Linus Torvalds
parent 3842b46de6
commit 3e1f064562
2 changed files with 40 additions and 18 deletions
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16
Documentation/vm/numa_memory_policy.txt
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@@ -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