drm/i915: Stop reconfiguring our shmemfs mountpoint

The filesystem reconfigure API is undergoing a transition, breaking our
current code. As we only set the default options, we can simply remove
the call to s_op->remount_fs(). In the future, when HW permits, we can
try re-enabling huge page support, albeit as suggested with new per-file
controls.

Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190808172226.18306-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c
index 099f339..5e6e8c9 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gemfs.c
+++ b/drivers/gpu/drm/i915/gem/i915_gemfs.c
@@ -20,31 +20,18 @@ int i915_gemfs_init(struct drm_i915_private *i915)
        if (!type)
                return -ENODEV;
 
-       gemfs = kern_mount(type);
-       if (IS_ERR(gemfs))
-               return PTR_ERR(gemfs);
-
        /*
-        * Enable huge-pages for objects that are at least HPAGE_PMD_SIZE, most
-        * likely 2M. Note that within_size may overallocate huge-pages, if say
-        * we allocate an object of size 2M + 4K, we may get 2M + 2M, but under
-        * memory pressure shmem should split any huge-pages which can be
-        * shrunk.
+        * By creating our own shmemfs mountpoint, we can pass in
+        * mount flags that better match our usecase.
+        *
+        * One example, although it is probably better with a per-file
+        * control, is selecting huge page allocations ("huge=within_size").
+        * Currently unused due to bandwidth issues (slow reads) on Broadwell+.
         */
 
-       if (has_transparent_hugepage()) {
-               struct super_block *sb = gemfs->mnt_sb;
-               /* FIXME: Disabled until we get W/A for read BW issue. */
-               char options[] = "huge=never";
-               int flags = 0;
-               int err;
-
-               err = sb->s_op->remount_fs(sb, &flags, options);
-               if (err) {
-                       kern_unmount(gemfs);
-                       return err;
-               }
-       }
+       gemfs = kern_mount(type);
+       if (IS_ERR(gemfs))
+               return PTR_ERR(gemfs);
 
        i915->mm.gemfs = gemfs;