From: Matthew Wilcox (Oracle) willy@infradead.org
[ Upstream commit 91abab83839aa2eba073e4a63c729832fdb27ea1 ]
If there is only a single entry at 0, the first time we call xas_next(), we return the entry. Unfortunately, all subsequent times we call xas_next(), we also return the entry at 0 instead of noticing that the xa_index is now greater than zero. This broke find_get_pages_contig().
Fixes: 64d3e9a9e0cc ("xarray: Step through an XArray") Reported-by: Kent Overstreet kent.overstreet@gmail.com Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org --- lib/test_xarray.c | 24 ++++++++++++++++++++++++ lib/xarray.c | 4 ++++ 2 files changed, 28 insertions(+)
diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 9d631a7b6a705..7df4f7f395bf2 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1110,6 +1110,28 @@ static noinline void check_find_entry(struct xarray *xa) XA_BUG_ON(xa, !xa_empty(xa)); }
+static noinline void check_move_tiny(struct xarray *xa) +{ + XA_STATE(xas, xa, 0); + + XA_BUG_ON(xa, !xa_empty(xa)); + rcu_read_lock(); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + rcu_read_unlock(); + xa_store_index(xa, 0, GFP_KERNEL); + rcu_read_lock(); + xas_set(&xas, 0); + XA_BUG_ON(xa, xas_next(&xas) != xa_mk_index(0)); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + xas_set(&xas, 0); + XA_BUG_ON(xa, xas_prev(&xas) != xa_mk_index(0)); + XA_BUG_ON(xa, xas_prev(&xas) != NULL); + rcu_read_unlock(); + xa_erase_index(xa, 0); + XA_BUG_ON(xa, !xa_empty(xa)); +} + static noinline void check_move_small(struct xarray *xa, unsigned long idx) { XA_STATE(xas, xa, 0); @@ -1217,6 +1239,8 @@ static noinline void check_move(struct xarray *xa)
xa_destroy(xa);
+ check_move_tiny(xa); + for (i = 0; i < 16; i++) check_move_small(xa, 1UL << i);
diff --git a/lib/xarray.c b/lib/xarray.c index 446b956c91888..1237c213f52bc 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -994,6 +994,8 @@ void *__xas_prev(struct xa_state *xas)
if (!xas_frozen(xas->xa_node)) xas->xa_index--; + if (!xas->xa_node) + return set_bounds(xas); if (xas_not_node(xas->xa_node)) return xas_load(xas);
@@ -1031,6 +1033,8 @@ void *__xas_next(struct xa_state *xas)
if (!xas_frozen(xas->xa_node)) xas->xa_index++; + if (!xas->xa_node) + return set_bounds(xas); if (xas_not_node(xas->xa_node)) return xas_load(xas);