diff options
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index fe49369f743a..04787973389b 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -452,6 +452,10 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = { .create = mpol_new_nodemask, .rebind = mpol_rebind_nodemask, }, + [MPOL_RANDOM] = { + .create = mpol_new_nodemask, + .rebind = mpol_rebind_nodemask, + }, }; static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist, @@ -899,6 +903,7 @@ static void get_policy_nodemask(struct mempolicy *pol, nodemask_t *nodes) case MPOL_PREFERRED: case MPOL_PREFERRED_MANY: case MPOL_WEIGHTED_INTERLEAVE: + case MPOL_RANDOM: *nodes = pol->nodes; break; case MPOL_LOCAL: @@ -1947,6 +1952,25 @@ static unsigned int interleave_nodes(struct mempolicy *policy) return nid; } +static unsigned int random_nodes(struct mempolicy *policy) +{ + unsigned int nid = first_node(policy->nodes); + unsigned int cpuset_mems_cookie; + nodemask_t nodemask; + unsigned int r; + + r = get_random_u32_below(read_once_policy_nodemask(policy, &nodemask)); + + /* to prevent miscount, use tsk->mems_allowed_seq to detect rebind */ + do { + cpuset_mems_cookie = read_mems_allowed_begin(); + while (r--) + nid = next_node_in(nid, policy->nodes); + } while (read_mems_allowed_retry(cpuset_mems_cookie)); + + return nid; +} + /* * Depending on the memory policy provide a node from which to allocate the * next slab entry. @@ -1992,6 +2016,9 @@ unsigned int mempolicy_slab_node(void) case MPOL_LOCAL: return node; + case MPOL_RANDOM: + return random_nodes(policy); + default: BUG(); } @@ -2067,6 +2094,33 @@ static unsigned int interleave_nid(struct mempolicy *pol, pgoff_t ilx) return nid; } +static unsigned int random_nid(struct mempolicy *pol, + struct vm_area_struct *vma, + pgoff_t ilx) +{ + nodemask_t nodemask; + unsigned int r, nnodes; + int i, nid; + + nnodes = read_once_policy_nodemask(pol, &nodemask); + if (!nnodes) + return numa_node_id(); + + /* + * QQQ + * Can we say hash of vma+ilx is sufficiently random but still + * stable in case of reliance on stable, as it appears is with + * mpol_misplaced and interleaving? + */ + r = hash_long((unsigned long)vma + ilx, + ilog2(roundup_pow_of_two(nnodes))); + + nid = first_node(nodemask); + for (i = 0; i < r; i++) + nid = next_node(nid, nodemask); + return nid; +} + /* * Return a nodemask representing a mempolicy for filtering nodes for * page allocation, together with preferred node id (or the input node id). @@ -2110,6 +2164,9 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol, weighted_interleave_nodes(pol) : weighted_interleave_nid(pol, ilx); break; + case MPOL_RANDOM: + *nid = random_nodes(pol); + break; } return nodemask; @@ -2172,6 +2229,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask) case MPOL_BIND: case MPOL_INTERLEAVE: case MPOL_WEIGHTED_INTERLEAVE: + case MPOL_RANDOM: *mask = mempolicy->nodes; break; @@ -2643,6 +2701,7 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b) case MPOL_PREFERRED: case MPOL_PREFERRED_MANY: case MPOL_WEIGHTED_INTERLEAVE: + case MPOL_RANDOM: return !!nodes_equal(a->nodes, b->nodes); case MPOL_LOCAL: return true; @@ -2817,6 +2876,10 @@ int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma, polnid = zone_to_nid(z->zone); break; + case MPOL_RANDOM: + polnid = random_nid(pol, vma, ilx); /* QQQ Hmmmm???? */ + break; + default: BUG(); } @@ -3162,6 +3225,7 @@ static const char * const policy_modes[] = [MPOL_WEIGHTED_INTERLEAVE] = "weighted interleave", [MPOL_LOCAL] = "local", [MPOL_PREFERRED_MANY] = "prefer (many)", + [MPOL_RANDOM] = "random", }; static int mpol_lookup_flag(char *str) @@ -3269,6 +3333,7 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) break; case MPOL_INTERLEAVE: case MPOL_WEIGHTED_INTERLEAVE: + case MPOL_RANDOM: /* * Default to online nodes with memory if no nodelist */ @@ -3400,6 +3465,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) case MPOL_BIND: case MPOL_INTERLEAVE: case MPOL_WEIGHTED_INTERLEAVE: + case MPOL_RANDOM: nodes = pol->nodes; break; default: |