mm: mempolicy: Add MPOL_NOOP (d3a71033) · Commits · 戴 / test

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() will map the pages PROT_NONE so that they will be migrated on the 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. [ Bug in early version of mpol_parse_str() reported by Fengguang Wu. ] Bug-Reported-by:

Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by:

Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by:

Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:

Ingo Molnar <mingo@kernel.org> Signed-off-by:

Mel Gorman <mgorman@suse.de>

include/uapi/linux/mempolicy.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 */
		};

mm/mempolicy.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -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);

		@@ -1147,7 +1147,7 @@ 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;
		@@ -2409,7 +2409,8 @@ static const char * const policy_modes[] =
		[MPOL_PREFERRED] = "prefer",
		[MPOL_BIND] = "bind",
		[MPOL_INTERLEAVE] = "interleave",
		[MPOL_LOCAL] = "local"
		[MPOL_LOCAL] = "local",
		[MPOL_NOOP] = "noop", /* should not actually be used */
		};


		@@ -2460,7 +2461,7 @@ int mpol_parse_str(char str, struct mempolicy *mpol, int no_context)
		break;
		}
		}
		if (mode >= MPOL_MAX)
		if (mode >= MPOL_MAX \|\| mode == MPOL_NOOP)
		goto out;

		switch (mode) {

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