From 7310895779624a11153d74a2132f01be6e360b7c Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 27 Jul 2023 12:22:24 -0400 Subject: [PATCH] mm: zswap: tighten up entry invalidation Removing a zswap entry from the tree is tied to an explicit operation that's supposed to drop the base reference: swap invalidation, exclusive load, duplicate store. Don't silently remove the entry on final put, but instead warn if an entry is in tree without reference. While in that diff context, convert a BUG_ON to a WARN_ON_ONCE. No need to crash on a refcount underflow. Link: https://lkml.kernel.org/r/20230727162343.1415598-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Reviewed-by: Yosry Ahmed Cc: Barry Song Cc: Domenico Cerasuolo Cc: Nhat Pham Cc: Seth Jennings Cc: Vitaly Wool Signed-off-by: Andrew Morton --- mm/zswap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 93707a1799b8a..ea921b25c245b 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -417,9 +417,9 @@ static void zswap_entry_put(struct zswap_tree *tree, { int refcount = --entry->refcount; - BUG_ON(refcount < 0); + WARN_ON_ONCE(refcount < 0); if (refcount == 0) { - zswap_rb_erase(&tree->rbroot, entry); + WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode)); zswap_free_entry(entry); } } -- 2.30.2