mempolicy: mpol_shared_policy_init() without pseudo-vma

mpol_shared_policy_init() does not need to use a pseudo-vma: it can use
sp_alloc() and sp_insert() directly, since the object's shared policy tree
is empty and inaccessible (needing no lock) at get_inode() time.

Link: https://lkml.kernel.org/r/3bef62d8-ae78-4c2-533-56a44ae425c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun heo <tj@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c18f0a1b97e3b834e817e7636371aa14edf80b04..b6461d7d200e807eb72512052a91362cd2a23944 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2736,30 +2736,30 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
        rwlock_init(&sp->lock);
 
        if (mpol) {
-               struct vm_area_struct pvma;
-               struct mempolicy *new;
+               struct sp_node *sn;
+               struct mempolicy *npol;
                NODEMASK_SCRATCH(scratch);
 
                if (!scratch)
                        goto put_mpol;
-               /* contextualize the tmpfs mount point mempolicy */
-               new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
-               if (IS_ERR(new))
+
+               /* contextualize the tmpfs mount point mempolicy to this file */
+               npol = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
+               if (IS_ERR(npol))
                        goto free_scratch; /* no valid nodemask intersection */
 
                task_lock(current);
-               ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
+               ret = mpol_set_nodemask(npol, &mpol->w.user_nodemask, scratch);
                task_unlock(current);
                if (ret)
-                       goto put_new;
-
-               /* Create pseudo-vma that contains just the policy */
-               vma_init(&pvma, NULL);
-               pvma.vm_end = TASK_SIZE;        /* policy covers entire file */
-               mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
-
-put_new:
-               mpol_put(new);                  /* drop initial ref */
+                       goto put_npol;
+
+               /* alloc node covering entire file; adds ref to file's npol */
+               sn = sp_alloc(0, MAX_LFS_FILESIZE >> PAGE_SHIFT, npol);
+               if (sn)
+                       sp_insert(sp, sn);
+put_npol:
+               mpol_put(npol); /* drop initial ref on file's npol */
 free_scratch:
                NODEMASK_SCRATCH_FREE(scratch);
 put_mpol: