The patch titled
Subject: mm: zswap: tighten up entry invalidation
has been added to the -mm mm-unstable branch. Its filename is
mm-zswap-tighten-up-entry-invalidation.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-tighten-up-entry-invalidation.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: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: zswap: tighten up entry invalidation
Date: Thu, 27 Jul 2023 12:22:24 -0400
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@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Seth Jennings <sjenning@xxxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/zswap.c~mm-zswap-tighten-up-entry-invalidation
+++ a/mm/zswap.c
@@ -417,9 +417,9 @@ static void zswap_entry_put(struct zswap
{
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);
}
}
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-kill-frontswap.patch
mm-kill-frontswap-fix.patch
mm-zswap-use-zswap_invalidate_entry-for-duplicates.patch
mm-zswap-tighten-up-entry-invalidation.patch
mm-zswap-kill-zswap_get_swap_cache_page.patch
