The patch titled
Subject: XArray: add cmpxchg order test
has been added to the -mm mm-unstable branch. Its filename is
xarray-add-cmpxchg-order-test.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/xarray-add-cmpxchg-order-test.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Subject: XArray: add cmpxchg order test
Date: Wed, 31 Jan 2024 14:51:25 -0800
XArray multi-index entries do not keep track of the order stored once the
entry is being marked as used with cmpxchg (conditionally replaced with
NULL). Add a test to check the order is actually lost. The test also
verifies the order and entries for all the tied indexes before and after
the NULL replacement with xa_cmpxchg.
Add another entry at 1 << order that keeps the node around and the order
information for the NULL-entry after xa_cmpxchg.
Link: https://lkml.kernel.org/r/20240131225125.1370598-3-mcgrof@xxxxxxxxxx
Signed-off-by: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_xarray.c | 54 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
--- a/lib/test_xarray.c~xarray-add-cmpxchg-order-test
+++ a/lib/test_xarray.c
@@ -423,6 +423,59 @@ static noinline void check_cmpxchg(struc
XA_BUG_ON(xa, !xa_empty(xa));
}
+static noinline void check_cmpxchg_order(struct xarray *xa)
+{
+#ifdef CONFIG_XARRAY_MULTI
+ void *FIVE = xa_mk_value(5);
+ unsigned int i, order = 3;
+
+ XA_BUG_ON(xa, xa_store_order(xa, 0, order, FIVE, GFP_KERNEL));
+
+ /* Check entry FIVE has the order saved */
+ XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != order);
+
+ /* Check all the tied indexes have the same entry and order */
+ for (i = 0; i < (1 << order); i++) {
+ XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+ XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+ }
+
+ /* Ensure that nothing is stored at index '1 << order' */
+ XA_BUG_ON(xa, xa_load(xa, 1 << order) != NULL);
+
+ /*
+ * Additionally, keep the node information and the order at
+ * '1 << order'
+ */
+ XA_BUG_ON(xa, xa_store_order(xa, 1 << order, order, FIVE, GFP_KERNEL));
+ for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
+ XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+ XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+ }
+
+ /* Conditionally replace FIVE entry at index '0' with NULL */
+ XA_BUG_ON(xa, xa_cmpxchg(xa, 0, FIVE, NULL, GFP_KERNEL) != FIVE);
+
+ /* Verify the order is lost at FIVE (and old) entries */
+ XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != 0);
+
+ /* Verify the order and entries are lost in all the tied indexes */
+ for (i = 0; i < (1 << order); i++) {
+ XA_BUG_ON(xa, xa_load(xa, i) != NULL);
+ XA_BUG_ON(xa, xa_get_order(xa, i) != 0);
+ }
+
+ /* Verify node and order are kept at '1 << order' */
+ for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
+ XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
+ XA_BUG_ON(xa, xa_get_order(xa, i) != order);
+ }
+
+ xa_store_order(xa, 0, BITS_PER_LONG - 1, NULL, GFP_KERNEL);
+ XA_BUG_ON(xa, !xa_empty(xa));
+#endif
+}
+
static noinline void check_reserve(struct xarray *xa)
{
void *entry;
@@ -1964,6 +2017,7 @@ static int xarray_checks(void)
check_xas_erase(&array);
check_insert(&array);
check_cmpxchg(&array);
+ check_cmpxchg_order(&array);
check_reserve(&array);
check_reserve(&xa0);
check_multi_store(&array);
_
Patches currently in -mm which might be from da.gomez@xxxxxxxxxxx are
xarray-add-cmpxchg-order-test.patch
