percpu: factor out pcpu_check_block_hint()

Factor out the pcpu_check_block_hint() helper, which will be useful
in the future. The new function checks if the allocation can likely
fit within the contig hint.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

diff --git a/mm/percpu.c b/mm/percpu.c
index 61339b3..5edc7bd 100644 (file)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -306,6 +306,25 @@ static unsigned long pcpu_block_off_to_off(int index, int off)
        return index * PCPU_BITMAP_BLOCK_BITS + off;
 }
 
+/**
+ * pcpu_check_block_hint - check against the contig hint
+ * @block: block of interest
+ * @bits: size of allocation
+ * @align: alignment of area (max PAGE_SIZE)
+ *
+ * Check to see if the allocation can fit in the block's contig hint.
+ * Note, a chunk uses the same hints as a block so this can also check against
+ * the chunk's contig hint.
+ */
+static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
+                                 size_t align)
+{
+       int bit_off = ALIGN(block->contig_hint_start, align) -
+               block->contig_hint_start;
+
+       return bit_off + bits <= block->contig_hint;
+}
+
 /*
  * pcpu_next_hint - determine which hint to use
  * @block: block of interest
@@ -1066,14 +1085,11 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
        int bit_off, bits, next_off;
 
        /*
-        * Check to see if the allocation can fit in the chunk's contig hint.
-        * This is an optimization to prevent scanning by assuming if it
-        * cannot fit in the global hint, there is memory pressure and creating
-        * a new chunk would happen soon.
+        * This is an optimization to prevent scanning by assuming if the
+        * allocation cannot fit in the global hint, there is memory pressure
+        * and creating a new chunk would happen soon.
         */
-       bit_off = ALIGN(chunk_md->contig_hint_start, align) -
-                 chunk_md->contig_hint_start;
-       if (bit_off + alloc_bits > chunk_md->contig_hint)
+       if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
                return -1;
 
        bit_off = pcpu_next_hint(chunk_md, alloc_bits);