From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79E7240A915; Sat, 28 Feb 2026 17:44:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300666; cv=none; b=gHVN5qscXkt8vdyaK0UaUpxQs+1n6rJsaJa2UQiaDuCF5+uIDx8p8tB7qpkn5zE5FLwEJRIgwOxd5SipWc7JYYO3f5hu8MpWtGZjXoFHtWpOmYL7BvTG+cW7Fn1nQD2SHnLa90ZQfsgwuC+iJ+oYJbJXXSlL+DqsIZRN6tTNYD4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300666; c=relaxed/simple; bh=kpHZapoyxabCm6cAD/gUJE9UyGbJ8uuPHKnXTWN8fPg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=StylydX5bMXTUxC+/3K83rbPc5O2sYwqI0ZfalI10IM8fzsZnUjNhYgVMSa+8Md12quq9ZYTqC4un0XhitsDkUR4U7NtjxUzAhkqAidVHRawv2yI0+3YOxKy3WlztO6bmjWMno1bAjmIb6tOj5GxuZuK3/uxZ930J2MHaJgrCOE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qcEH5xr2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qcEH5xr2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DD4CC19425; Sat, 28 Feb 2026 17:44:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772300666; bh=kpHZapoyxabCm6cAD/gUJE9UyGbJ8uuPHKnXTWN8fPg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qcEH5xr2DbbCWbbKYievTbbKZt86/GnntqcxmyqsYUeX0eZZcRf0SG8ZVEzQ4t0u+ eAhfLSWSdw5Q/KlNsoHhci4D1rUH+2/H576OKC7OXx+eTxTUnHU8hLs/Sf4kkCb0CP 0WFBRj2ClVubNYPiU9ci8cCFpxLTjgDMOczA2vgCFTc+6/ToRKOzW99P6lbAiBOXc5 X2ZxPwM771CX1lpcZT3KE/rKqwbfipk8947lARQK6E9PdK8thF0oJBA80YfqGN2FCH AKpdtSHLB+hpLR02bflQvG6yfNATGrCziPYf5CEl6hzVc3GUR1gQFZTh9w8ridosW1 6vRc1RGC6IVXg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vlastimil Babka , kernel test robot , Harry Yoo , Suren Baghdasaryan , "Liam R. Howlett" , Sasha Levin Subject: [PATCH 6.19 703/844] mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on_cache() Date: Sat, 28 Feb 2026 12:30:16 -0500 Message-ID: <20260228173244.1509663-704-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228173244.1509663-1-sashal@kernel.org> References: <20260228173244.1509663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Vlastimil Babka [ Upstream commit b55b423e8518361124ff0a9e15df431b3682ee4f ] After we submit the rcu_free sheaves to call_rcu() we need to make sure the rcu callbacks complete. kvfree_rcu_barrier() does that via flush_all_rcu_sheaves() but kvfree_rcu_barrier_on_cache() doesn't. Fix that. This currently causes no issues because the caches with sheaves we have are never destroyed. The problem flagged by kernel test robot was reported for a patch that enables sheaves for (almost) all caches, and occurred only with CONFIG_KASAN. Harry Yoo found the root cause [1]: It turns out the object freed by sheaf_flush_unused() was in KASAN percpu quarantine list (confirmed by dumping the list) by the time __kmem_cache_shutdown() returns an error. Quarantined objects are supposed to be flushed by kasan_cache_shutdown(), but things go wrong if the rcu callback (rcu_free_sheaf_nobarn()) is processed after kasan_cache_shutdown() finishes. That's why rcu_barrier() in __kmem_cache_shutdown() didn't help, because it's called after kasan_cache_shutdown(). Calling rcu_barrier() in kvfree_rcu_barrier_on_cache() guarantees that it'll be added to the quarantine list before kasan_cache_shutdown() is called. So it's a valid fix! [1] https://lore.kernel.org/all/aWd6f3jERlrB5yeF@hyeyoo/ Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202601121442.c530bed3-lkp@intel.com Fixes: 0f35040de593 ("mm/slab: introduce kvfree_rcu_barrier_on_cache() for cache destruction") Cc: stable@vger.kernel.org Reviewed-by: Harry Yoo Tested-by: Harry Yoo Reviewed-by: Suren Baghdasaryan Reviewed-by: Liam R. Howlett Signed-off-by: Vlastimil Babka Signed-off-by: Sasha Levin --- mm/slab_common.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index eed7ea556cb1a..ee994ec7f251e 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -2133,8 +2133,11 @@ EXPORT_SYMBOL_GPL(kvfree_rcu_barrier); */ void kvfree_rcu_barrier_on_cache(struct kmem_cache *s) { - if (s->cpu_sheaves) + if (s->cpu_sheaves) { flush_rcu_sheaves_on_cache(s); + rcu_barrier(); + } + /* * TODO: Introduce a version of __kvfree_rcu_barrier() that works * on a specific slab cache. -- 2.51.0