mempolicy: mPOL_PREFERRED cleanups for "local allocation"
Here are a couple of "cleanups" for MPOL_PREFERRED behavior when v.preferred_node < 0 -- i.e., "local allocation": 1) [do_]get_mempolicy() calls the now renamed get_policy_nodemask() to fetch the nodemask associated with a policy. Currently, get_policy_nodemask() returns the set of nodes with memory, when the policy 'mode' is 'PREFERRED, and the preferred_node is < 0. Change to return an empty nodemask, as this is what was specified to achieve "local allocation". 2) When a task is moved into a [new] cpuset, mpol_rebind_policy() is called to adjust any task and vma policy nodes to be valid in the new cpuset. However, when the policy is MPOL_PREFERRED, and the preferred_node is <0, no rebind is necessary. The "local allocation" indication is valid in any cpuset. Existing code will "do the right thing" because node_remap() will just return the argument node when it is outside of the valid range of node ids. However, I think it is clearer and cleaner to skip the remap explicitly in this case. 3) mpol_to_str() produces a printable, "human readable" string from a struct mempolicy. For MPOL_PREFERRED with preferred_node <0, show "local", as this indicates local allocation, as the task migrates among nodes. Note that this matches the usage of "local allocation" in libnuma() and numactl. Without this change, I believe that node_set() [via set_bit()] will set bit 31, resulting in a misleading display. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -645,11 +645,9 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
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*nodes = p->v.nodes;
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break;
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case MPOL_PREFERRED:
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/* or use current node instead of memory_map? */
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if (p->v.preferred_node < 0)
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*nodes = node_states[N_HIGH_MEMORY];
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else
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if (p->v.preferred_node >= 0)
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node_set(p->v.preferred_node, *nodes);
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/* else return empty node mask for local allocation */
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break;
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default:
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BUG();
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@ -804,7 +802,7 @@ int do_migrate_pages(struct mm_struct *mm,
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int err = 0;
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nodemask_t tmp;
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down_read(&mm->mmap_sem);
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down_read(&mm->mmap_sem);
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err = migrate_vmas(mm, from_nodes, to_nodes, flags);
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if (err)
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@ -1948,10 +1946,12 @@ void numa_default_policy(void)
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}
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/*
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* Display pages allocated per node and memory policy via /proc.
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* "local" is pseudo-policy: MPOL_PREFERRED with preferred_node == -1
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* Used only for mpol_to_str()
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*/
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#define MPOL_LOCAL (MPOL_INTERLEAVE + 1)
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static const char * const policy_types[] =
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{ "default", "prefer", "bind", "interleave" };
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{ "default", "prefer", "bind", "interleave", "local" };
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/*
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* Convert a mempolicy into a string.
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@ -1962,6 +1962,7 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
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{
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char *p = buffer;
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int l;
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int nid;
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nodemask_t nodes;
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unsigned short mode;
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unsigned short flags = pol ? pol->flags : 0;
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@ -1978,7 +1979,11 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
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case MPOL_PREFERRED:
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nodes_clear(nodes);
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node_set(pol->v.preferred_node, nodes);
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nid = pol->v.preferred_node;
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if (nid < 0)
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mode = MPOL_LOCAL; /* pseudo-policy */
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else
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node_set(nid, nodes);
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break;
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case MPOL_BIND:
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@ -1993,8 +1998,8 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
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}
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l = strlen(policy_types[mode]);
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if (buffer + maxlen < p + l + 1)
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return -ENOSPC;
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if (buffer + maxlen < p + l + 1)
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return -ENOSPC;
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strcpy(p, policy_types[mode]);
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p += l;
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@ -2093,6 +2098,9 @@ static inline void check_huge_range(struct vm_area_struct *vma,
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}
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#endif
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/*
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* Display pages allocated per node and memory policy via /proc.
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*/
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int show_numa_map(struct seq_file *m, void *v)
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{
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struct proc_maps_private *priv = m->private;
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