+ mm-zswap-interact-directly-with-zsmalloc-fix.patch added to mm-unstable branch

+ mm-zswap-interact-directly-with-zsmalloc-fix.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: zswap: interact directly with zsmalloc fix
has been added to the -mm mm-unstable branch.  Its filename is
     mm-zswap-interact-directly-with-zsmalloc-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-interact-directly-with-zsmalloc-fix.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: mm: zswap: interact directly with zsmalloc fix
Date: Mon, 15 Sep 2025 10:56:15 -0400

Yosry points out that the default compressor check only applies when
something else is configured and we fall back, but not if it was
configured out of the box but isn't available.  Move the test.  Kconfig
should not permit this, so replace the pr_err() with a WARN.

Link: https://lkml.kernel.org/r/20250915153640.GA828739@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.se>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zswap.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/mm/zswap.c~mm-zswap-interact-directly-with-zsmalloc-fix
+++ a/mm/zswap.c
@@ -306,12 +306,12 @@ static struct zswap_pool *__zswap_pool_c
 		       zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
 		param_free_charp(&zswap_compressor);
 		zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
-		if (!crypto_has_acomp(zswap_compressor, 0, 0)) {
-			pr_err("default compressor %s not available\n",
-			       zswap_compressor);
-			zswap_compressor = ZSWAP_PARAM_UNSET;
-			return NULL;
-		}
+	}
+
+	/* Default compressor should be available. Kconfig bug? */
+	if (WARN_ON_ONCE(!crypto_has_acomp(zswap_compressor, 0, 0))) {
+		zswap_compressor = ZSWAP_PARAM_UNSET;
+		return NULL;
 	}
 
 	return zswap_pool_create(zswap_compressor);
_

Patches currently in -mm which might be from hannes@cmpxchg.org are

mm-zswap-interact-directly-with-zsmalloc.patch
mm-zswap-interact-directly-with-zsmalloc-fix.patch
mm-remove-unused-zpool-layer.patch
mm-zpdesc-minor-naming-and-comment-corrections.patch