mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

Implement the missing huge page allocation functionality while obeying the
preferred node semantics.  This is similar to the implementation for
general page allocation, as it uses a fallback mechanism to try multiple
preferred nodes first, and then all other nodes.

To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function
in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY.

[[email protected]: fix compiling issue when merging with other hugetlb patch]
[Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue]
[[email protected]: suggest to remove the #ifdef CONFIG_NUMA check]
[[email protected]: add helpers to avoid ifdefs]
  Link: https://lore.kernel.org/r/[email protected]
  Link: https://lkml.kernel.org/r/[email protected]
  Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: initialize page to NULL in alloc_buddy_huge_page_with_mpol()]
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lore.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ben Widawsky <[email protected]>
Signed-off-by: Feng Tang <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Co-developed-by: Feng Tang <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 4ca025e2a77e..4091692bed8c 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -186,6 +186,12 @@ extern void mpol_put_task_policy(struct task_struct *);
 
 extern bool numa_demotion_enabled;
 
+static inline bool mpol_is_preferred_many(struct mempolicy *pol)
+{
+	return  (pol->mode == MPOL_PREFERRED_MANY);
+}
+
+
 #else
 
 struct mempolicy {};
@@ -296,5 +302,11 @@ static inline nodemask_t *policy_nodemask_current(gfp_t gfp)
 }
 
 #define numa_demotion_enabled	false
+
+static inline bool mpol_is_preferred_many(struct mempolicy *pol)
+{
+	return  false;
+}
+
 #endif /* CONFIG_NUMA */
 #endif