diff options
| author | Johannes Weiner <hannes@cmpxchg.org> | 2016-12-12 16:43:43 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 18:55:08 -0800 |
| commit | 6d75f366b9242f9b17ed7d0b0604d7460f818f21 (patch) | |
| tree | d2225813a4c3f435e79273780eac7b1f7b2ecf67 /mm/migrate.c | |
| parent | f7942430e40f14c6d2ca48a1875add509938c07d (diff) | |
| download | linux-6d75f366b9242f9b17ed7d0b0604d7460f818f21.tar.gz linux-6d75f366b9242f9b17ed7d0b0604d7460f818f21.tar.bz2 linux-6d75f366b9242f9b17ed7d0b0604d7460f818f21.zip | |
lib: radix-tree: check accounting of existing slot replacement users
The bug in khugepaged fixed earlier in this series shows that radix tree
slot replacement is fragile; and it will become more so when not only
NULL<->!NULL transitions need to be caught but transitions from and to
exceptional entries as well. We need checks.
Re-implement radix_tree_replace_slot() on top of the sanity-checked
__radix_tree_replace(). This requires existing callers to also pass the
radix tree root, but it'll warn us when somebody replaces slots with
contents that need proper accounting (transitions between NULL entries,
real entries, exceptional entries) and where a replacement through the
slot pointer would corrupt the radix tree node counts.
Link: http://lkml.kernel.org/r/20161117193021.GB23430@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 66ce6b490b13..0ed24b1fa77b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -482,7 +482,7 @@ int migrate_page_move_mapping(struct address_space *mapping, SetPageDirty(newpage); } - radix_tree_replace_slot(pslot, newpage); + radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); /* * Drop cache reference from old page by unfreezing @@ -556,7 +556,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping, get_page(newpage); - radix_tree_replace_slot(pslot, newpage); + radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); page_ref_unfreeze(page, expected_count - 1); |