The patch titled
Subject: mm: workingset: restore refault tracking for single-page files
has been added to the -mm tree. Its filename is
mm-workingset-restore-refault-tracking-for-single-page-files.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-workingset-restore-refault-tracking-for-single-page-files.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-workingset-restore-refault-tracking-for-single-page-files.patch
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From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: workingset: restore refault tracking for single-page files
Shadow entries in the page cache used to be accounted behind the radix
tree implementation's back in the upper bits of node->count, and the radix
tree code extending a single-entry tree with a shadow entry in root->rnode
would corrupt that counter. As a result, we could not put shadow entries
at index 0 if the tree didn't have any other entries, and that means no
refault detection for any single-page file.
Now that the shadow entries are tracked natively in the radix tree's
exceptional counter, this is no longer necessary. Extending and shrinking
the tree from and to single entries in root->rnode now does the right
thing when the entry is exceptional, remove that limitation.
Link: http://lkml.kernel.org/r/20161117193244.GF23430@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff -puN mm/filemap.c~mm-workingset-restore-refault-tracking-for-single-page-files mm/filemap.c
--- a/mm/filemap.c~mm-workingset-restore-refault-tracking-for-single-page-files
+++ a/mm/filemap.c
@@ -167,14 +167,7 @@ static void page_cache_tree_delete(struc
__radix_tree_lookup(&mapping->page_tree, page->index + i,
&node, &slot);
- if (!node) {
- VM_BUG_ON_PAGE(nr != 1, page);
- /*
- * We need a node to properly account shadow
- * entries. Don't plant any without. XXX
- */
- shadow = NULL;
- }
+ VM_BUG_ON_PAGE(!node && nr != 1, page);
radix_tree_clear_tags(&mapping->page_tree, node, slot);
__radix_tree_replace(&mapping->page_tree, node, slot, shadow,
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-khugepaged-close-use-after-free-race-during-shmem-collapsing.patch
mm-khugepaged-fix-radix-tree-node-leak-in-shmem-collapse-error-path.patch
mm-workingset-turn-shadow-node-shrinker-bugs-into-warnings.patch
lib-radix-tree-native-accounting-of-exceptional-entries.patch
lib-radix-tree-check-accounting-of-existing-slot-replacement-users.patch
lib-radix-tree-add-entry-deletion-support-to-__radix_tree_replace.patch
lib-radix-tree-update-callback-for-changing-leaf-nodes.patch
mm-workingset-move-shadow-entry-tracking-to-radix-tree-exceptional-tracking.patch
mm-workingset-restore-refault-tracking-for-single-page-files.patch
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