Merge tag 'drm-misc-fixes-2021-07-13' of git://anongit.freedesktop.org/drm/drm-misc...

[linux-2.6-microblaze.git] / mm / percpu-vm.c

diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 8d3844b..2054c92 100644 (file)
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -303,6 +303,9 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
  * For each cpu, depopulate and unmap pages [@page_start,@page_end)
  * from @chunk.
  *
+ * Caller is required to call pcpu_post_unmap_tlb_flush() if not returning the
+ * region back to vmalloc() which will lazily flush the tlb.
+ *
  * CONTEXT:
  * pcpu_alloc_mutex.
  */
@@ -324,18 +327,15 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
 
        pcpu_unmap_pages(chunk, pages, page_start, page_end);
 
-       /* no need to flush tlb, vmalloc will handle it lazily */
-
        pcpu_free_pages(chunk, pages, page_start, page_end);
 }
 
-static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
-                                           gfp_t gfp)
+static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
 {
        struct pcpu_chunk *chunk;
        struct vm_struct **vms;
 
-       chunk = pcpu_alloc_chunk(type, gfp);
+       chunk = pcpu_alloc_chunk(gfp);
        if (!chunk)
                return NULL;
 
@@ -378,3 +378,33 @@ static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
        /* no extra restriction */
        return 0;
 }
+
+/**
+ * pcpu_should_reclaim_chunk - determine if a chunk should go into reclaim
+ * @chunk: chunk of interest
+ *
+ * This is the entry point for percpu reclaim.  If a chunk qualifies, it is then
+ * isolated and managed in separate lists at the back of pcpu_slot: sidelined
+ * and to_depopulate respectively.  The to_depopulate list holds chunks slated
+ * for depopulation.  They no longer contribute to pcpu_nr_empty_pop_pages once
+ * they are on this list.  Once depopulated, they are moved onto the sidelined
+ * list which enables them to be pulled back in for allocation if no other chunk
+ * can suffice the allocation.
+ */
+static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
+{
+       /* do not reclaim either the first chunk or reserved chunk */
+       if (chunk == pcpu_first_chunk || chunk == pcpu_reserved_chunk)
+               return false;
+
+       /*
+        * If it is isolated, it may be on the sidelined list so move it back to
+        * the to_depopulate list.  If we hit at least 1/4 pages empty pages AND
+        * there is no system-wide shortage of empty pages aside from this
+        * chunk, move it to the to_depopulate list.
+        */
+       return ((chunk->isolated && chunk->nr_empty_pop_pages) ||
+               (pcpu_nr_empty_pop_pages >
+                (PCPU_EMPTY_POP_PAGES_HIGH + chunk->nr_empty_pop_pages) &&
+                chunk->nr_empty_pop_pages >= chunk->nr_pages / 4));
+}