On Mon, Jan 14, 2019 at 09:47:41PM +0300, Cyrill Gorcunov wrote: > Since the mark is used as an array index we should use > preincrement to not access the XA_MARK_MAX index.
But XA_MARK_MAX is inclusive: include/linux/xarray.h:#define XA_MARK_MAX XA_MARK_2 so we actually want to access XA_MARK_MAX. Now, we don't have a test in the test-suite that fails as a result of your patch, so that needs to get fixed. How about this: From: Matthew Wilcox <[email protected]> Date: Mon, 14 Jan 2019 13:57:31 -0500 Subject: [PATCH] XArray tests: Check mark 2 gets squashed We do not currently check that the loop in xas_squash_marks() doesn't have an off-by-one error in it. It didn't, but a patch which introduced an off-by-one error wasn't caught by any existing test. Switch the roles of XA_MARK_1 and XA_MARK_2 to catch that bug. Reported-by: Cyrill Gorcunov <[email protected]> Signed-off-by: Matthew Wilcox <[email protected]> --- lib/test_xarray.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 3cf17338b0a4..c596a957f764 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -199,7 +199,7 @@ static noinline void check_xa_mark_1(struct xarray *xa, unsigned long index) XA_BUG_ON(xa, xa_store_index(xa, index + 1, GFP_KERNEL)); xa_set_mark(xa, index + 1, XA_MARK_0); XA_BUG_ON(xa, xa_store_index(xa, index + 2, GFP_KERNEL)); - xa_set_mark(xa, index + 2, XA_MARK_1); + xa_set_mark(xa, index + 2, XA_MARK_2); XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL)); xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL); @@ -209,8 +209,8 @@ static noinline void check_xa_mark_1(struct xarray *xa, unsigned long index) void *entry; XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0)); - XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_1)); - XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_2)); + XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_1)); + XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_2)); /* We should see two elements in the array */ rcu_read_lock(); -- 2.20.1
