Commit-ID: 0719b9688bfedbc6ab12e863a0b2daf37d319f8d
Gitweb: http://git.kernel.org/tip/0719b9688bfedbc6ab12e863a0b2daf37d319f8d
Author: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
AuthorDate: Mon, 16 Jan 2012 14:43:29 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 26 Sep 2012 11:48:33 +0200
mm/mpol: Add MPOL_MF_NOOP
This patch augments the MPOL_MF_LAZY feature by adding a "NOOP"
policy to mbind(). When the NOOP policy is used with the 'MOVE
and 'LAZY flags, mbind() [check_range()] will walk the specified
range and unmap eligible pages so that they will be migrated on
next touch.
This allows an application to prepare for a new phase of operation
where different regions of shared storage will be assigned to
worker threads, w/o changing policy. Note that we could just use
"default" policy in this case. However, this also allows an
application to request that pages be migrated, only if necessary,
to follow any arbitrary policy that might currently apply to a
range of pages, without knowing the policy, or without specifying
multiple mbind()s for ranges with different policies.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/mempolicy.h | 1 +
mm/mempolicy.c | 8 ++++----
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 73683fb..9fe1ab1 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -21,6 +21,7 @@ enum {
MPOL_BIND,
MPOL_INTERLEAVE,
MPOL_LOCAL,
+ MPOL_NOOP, /* retain existing policy for range */
MPOL_MAX, /* always last member of enum */
};
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 52c268b..0de12e2 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -251,10 +251,10 @@ 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 (mode == MPOL_DEFAULT) {
+ if (mode == MPOL_DEFAULT || mode == MPOL_NOOP) {
if (nodes && !nodes_empty(*nodes))
return ERR_PTR(-EINVAL);
- return NULL; /* simply delete any existing policy */
+ return NULL;
}
VM_BUG_ON(!nodes);
@@ -1137,7 +1137,7 @@ static long do_mbind(unsigned long start, unsigned long len,
if (start & ~PAGE_MASK)
return -EINVAL;
- if (mode == MPOL_DEFAULT)
+ if (mode == MPOL_DEFAULT || mode == MPOL_NOOP)
flags &= ~MPOL_MF_STRICT;
len = (len + PAGE_SIZE - 1) & PAGE_MASK;
@@ -1189,7 +1189,7 @@ static long do_mbind(unsigned long start, unsigned long len,
flags | MPOL_MF_INVERT, &pagelist);
err = PTR_ERR(vma); /* maybe ... */
- if (!IS_ERR(vma))
+ if (!IS_ERR(vma) && mode != MPOL_NOOP)
err = mbind_range(mm, start, end, new);
if (!err) {
--
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