pagewalk: separate function pointers from iterator data

The mm_walk structure currently mixed data and code.  Split out the
operations vectors into a new mm_walk_ops structure, and while we are
changing the API also declare the mm_walk structure inside the
walk_page_range and walk_page_vma functions.

Based on patch from Linus Torvalds.

Link: https://lore.kernel.org/r/20190828141955.22210-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 11 insertions, 12 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4c3af5d71ab1..9b2516a76be2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5283,17 +5283,16 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
         return 0;
 }
 
+static const struct mm_walk_ops precharge_walk_ops = {
+        .pmd_entry      = mem_cgroup_count_precharge_pte_range,
+};
+
 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
 {
         unsigned long precharge;
 
-        struct mm_walk mem_cgroup_count_precharge_walk = {
-                .pmd_entry = mem_cgroup_count_precharge_pte_range,
-                .mm = mm,
-        };
         down_read(&mm->mmap_sem);
-        walk_page_range(0, mm->highest_vm_end,
-                        &mem_cgroup_count_precharge_walk);
+        walk_page_range(mm, 0, mm->highest_vm_end, &precharge_walk_ops, NULL);
         up_read(&mm->mmap_sem);
 
         precharge = mc.precharge;
@@ -5562,13 +5561,12 @@ put:			/* get_mctgt_type() gets the page */
         return ret;
 }
 
+static const struct mm_walk_ops charge_walk_ops = {
+        .pmd_entry      = mem_cgroup_move_charge_pte_range,
+};
+
 static void mem_cgroup_move_charge(void)
 {
-        struct mm_walk mem_cgroup_move_charge_walk = {
-                .pmd_entry = mem_cgroup_move_charge_pte_range,
-                .mm = mc.mm,
-        };
-
         lru_add_drain_all();
         /*
          * Signal lock_page_memcg() to take the memcg's move_lock
@@ -5594,7 +5592,8 @@ retry:
          * When we have consumed all precharges and failed in doing
          * additional charge, the page walk just aborts.
          */
-        walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk);
+        walk_page_range(mc.mm, 0, mc.mm->highest_vm_end, &charge_walk_ops,
+                        NULL);
 
         up_read(&mc.mm->mmap_sem);
         atomic_dec(&mc.from->moving_account);