From nobody Sat Jul 25 03:05:31 2026 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 70CFC3A782B for ; Mon, 20 Jul 2026 07:13:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784531630; cv=none; b=WCzZvJz4K/klRVF6ljJ6bwfJbfWX77o8Qz+cgmmhj1HR5JIdaCqPweDHQJ8BasbGEVd5rQ9STpdrD929z7Kgu3K4GLTgCQCuU/haXvF40JnPDD8cqCaPJEwXJBSr5Z9ULd/+j2QcFBaAJ/LUumylvL3swXlvxiaNDxT0JVKjqCo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784531630; c=relaxed/simple; bh=00GYCO6PUf6bLMEiTn+Snlq4YEX+lXXOA6mXHIG9Qm8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=txU6vt4TB1v6F1cROOBJcANbY13NBRrRu8avMr5M2X2pC/bbtXj4ghgnMxi3HbUoh8nrkUiaFZcvZgXCgvrBNkejnfrFFrNwepVBR6HMFZPF/XyIrFutpOZ6gHJqz4AslQR2fwKdEX+9xz7mppTRX6Zys9dyHoREWur/hucXXX4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.170]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4h3WvM1l8CzYQttB for ; Mon, 20 Jul 2026 15:13:19 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 747F54056E for ; Mon, 20 Jul 2026 15:13:44 +0800 (CST) Received: from huaweicloud.com (unknown [10.166.163.161]) by APP3 (Coremail) with UTF8SMTPA id _Ch0CgAX4qKnyl1qax5+Bw--.27530S3; Mon, 20 Jul 2026 15:13:44 +0800 (CST) From: Kemeng Shi To: chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/4] mm, swap: Fix potential NULL dereference when trying a sleep table allocation Date: Mon, 20 Jul 2026 15:13:39 +0800 Message-Id: <20260720071342.50742-2-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20260720071342.50742-1-shikemeng@huaweicloud.com> References: <20260720071342.50742-1-shikemeng@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgAX4qKnyl1qax5+Bw--.27530S3 X-Coremail-Antispam: 1UD129KBjvJXoWxGF4fXFW7WF1fCFWfXF4kCrg_yoW5XF1kpF 9Yg3s8Kr45Jr9xGrsIy3Wqq34agw40gryDGw1xGr1293ZxXr4xXF1DCrWYvF95CF1kJr90 gr1Utw17ua1q9wUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r1I6r4UM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0D M2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjx v20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1l F7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkF7I0En4kS14v26r1q6r 43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWx JVW8Jr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUHc_fUUUUU = X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ The root cause of this issue is because multi-tables are updated in non atomic context. To be more specific, the issue could be triggerred as following: swap_alloc_fast swap_cluster_populate() /* Try a sleep allocation */ spin_unlock(&ci->lock); swap_cluster_alloc_table() rcu_assign_pointer(ci->table, table); ci =3D swap_cluster_lock(si, offset) cluster_is_usable(ci, order=EF=BC=89 if (!cluster_table_is_alloced(ci)) // ok alloc_swap_scan_cluster() cluster_scan_range() __swap_table_get() /* free table when more table allocation fails */ ci->memcg_table =3D kzalloc_obj(*ci->memcg_table, gfp); if (!ci->memcg_table) swap_cluster_free_table() rcu_assign_pointer(ci->table, NULL); table =3D rcu_dereference_check(ci->table, lockdep_is_held(&ci->lock)); atomic_long_read(&table[off]); // NULL dereference Fix the issue by updating allocated tables in atomic context. Fixes: 2fe7a6f5024b8 ("mm/memcg, swap: store cgroup id in cluster table dir= ectly") Signed-off-by: Kemeng Shi --- mm/swapfile.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 615d90867111..d29062d9c3cd 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -490,6 +490,20 @@ static int swap_cluster_alloc_table(struct swap_cluste= r_info *ci, gfp_t gfp) return 0; } =20 +static void swap_cluster_copy_table(struct swap_cluster_info *d_ci, + struct swap_cluster_info *s_ci) +{ + rcu_assign_pointer(d_ci->table, rcu_access_pointer(s_ci->table)); + +#ifdef CONFIG_MEMCG + d_ci->memcg_table =3D s_ci->memcg_table; +#endif + +#if !SWAP_TABLE_HAS_ZEROFLAG + d_ci->zero_bitmap =3D s_ci->zero_bitmap; +#endif +} + /* * Sanity check to ensure nothing leaked, and the specified range is empty. * One special case is that bad slots can't be freed, so check the number = of @@ -527,6 +541,7 @@ static struct swap_cluster_info * swap_cluster_populate(struct swap_info_struct *si, struct swap_cluster_info *ci) { + struct swap_cluster_info tmp_ci; int ret; =20 /* @@ -552,7 +567,8 @@ swap_cluster_populate(struct swap_info_struct *si, spin_unlock(&si->global_cluster_lock); local_unlock(&percpu_swap_cluster.lock); =20 - ret =3D swap_cluster_alloc_table(ci, __GFP_HIGH | __GFP_NOMEMALLOC | + tmp_ci =3D *ci; + ret =3D swap_cluster_alloc_table(&tmp_ci, __GFP_HIGH | __GFP_NOMEMALLOC | GFP_KERNEL); =20 /* @@ -573,6 +589,9 @@ swap_cluster_populate(struct swap_info_struct *si, spin_unlock(&ci->lock); return NULL; } + + /* Update tables in atomic context */ + swap_cluster_copy_table(ci, &tmp_ci); return ci; } =20 --=20 2.36.1 From nobody Sat Jul 25 03:05:31 2026 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 C69B73B71B0 for ; Mon, 20 Jul 2026 07:13:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; 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spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.170]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4h3WvM5Ps3zYQtvd for ; Mon, 20 Jul 2026 15:13:19 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id F1C9340570 for ; Mon, 20 Jul 2026 15:13:44 +0800 (CST) Received: from huaweicloud.com (unknown [10.166.163.161]) by APP3 (Coremail) with UTF8SMTPA id _Ch0CgAX4qKnyl1qax5+Bw--.27530S4; Mon, 20 Jul 2026 15:13:44 +0800 (CST) From: Kemeng Shi To: chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] mm, swap: Move setup_swap_clusters_info() after SWP_SOLIDSTATE initialization Date: Mon, 20 Jul 2026 15:13:40 +0800 Message-Id: <20260720071342.50742-3-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20260720071342.50742-1-shikemeng@huaweicloud.com> References: <20260720071342.50742-1-shikemeng@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgAX4qKnyl1qax5+Bw--.27530S4 X-Coremail-Antispam: 1UD129KBjvJXoW7urWrJFy7Zr4xZF4DXr18Zrb_yoW8GF4DpF n5Kas8Cr4Utr1fWw48Aw1DW34Ygw1FkF4Utay3Xw43uwn7Ar1Igryrt3Z8Zrn8GFn5AFWD Ww1xZ3s7uF1q9wUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0D M2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjx v20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1l F7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkF7I0En4kS14v26r1q6r 43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWx JVW8Jr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUTE__UUUUU = X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ Content-Type: text/plain; charset="utf-8" In setup_swap_clusters_info(), SWP_SOLIDSTATE is used to decide global_cluster allocation. Move setup_swap_clusters_info() after SWP_SOLIDSTATE initialization to avoid unneeded global_cluster allocation. Fixes: 451c6326105b2 ("mm, swap: clean up swapon process and locking") Signed-off-by: Kemeng Shi Reviewed-by: Luiz Capitulino --- mm/swapfile.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index d29062d9c3cd..81c4040912be 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3607,11 +3607,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, special= file, int, swap_flags) =20 maxpages =3D si->max; =20 - /* Set up the swap cluster info */ - error =3D setup_swap_clusters_info(si, swap_header, maxpages); - if (error) - goto bad_swap_unlock_inode; - if (si->bdev && bdev_stable_writes(si->bdev)) si->flags |=3D SWP_STABLE_WRITES; =20 @@ -3625,6 +3620,14 @@ SYSCALL_DEFINE2(swapon, const char __user *, special= file, int, swap_flags) inced_nr_rotate_swap =3D true; } =20 + /* + * Set up the swap cluster info. SWP_SOLIDSTATE is used for + * global_cluster allocation + */ + error =3D setup_swap_clusters_info(si, swap_header, maxpages); + if (error) + goto bad_swap_unlock_inode; + if ((swap_flags & SWAP_FLAG_DISCARD) && si->bdev && bdev_max_discard_sectors(si->bdev)) { /* --=20 2.36.1 From nobody Sat Jul 25 03:05:31 2026 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 4C92C3B71B1 for ; Mon, 20 Jul 2026 07:13:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784531629; cv=none; b=tJ9doL9scqkDIGtM4RyE9SohgVs5ACKXDRyvIAPHbExa8RSTgXX+PV4QeClJJQ/4MWNbfdWtjLZBFgdfkB1s1s7wdvqQUtOYIsYqqid1PogL1j6UdDxbdcwGSUSf+HwpO9mXdgb+/5NW6SKcenrO5aXWM734OW+lsT/nZd+7hR8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784531629; c=relaxed/simple; bh=HiiSdhJO/z240ab924F4yd0WyVpbeRjevb22Vom2FDY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=e84Eslgl2lZps+E226WlbR9rpNvJW+7SaMHRa8ybHTz7JzSi/AKEXyBetLZxiR1HQJXnUjF1V0F/wyL7TEt05TZ17JfPwWW82lXR9R0eaMwWXYv+9JqKpig9+ugJO5748LyGaqy+Tyvay1BI525x9pviPF+w8It9GG8g5KEkrlY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.170]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4h3WvN1lwFzYQtvC for ; Mon, 20 Jul 2026 15:13:20 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 72BA14056E for ; Mon, 20 Jul 2026 15:13:45 +0800 (CST) Received: from huaweicloud.com (unknown [10.166.163.161]) by APP3 (Coremail) with UTF8SMTPA id _Ch0CgAX4qKnyl1qax5+Bw--.27530S5; Mon, 20 Jul 2026 15:13:45 +0800 (CST) From: Kemeng Shi To: chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/4] mm, swap: return early from swap_extend_table_try_free() on first non-zero entry Date: Mon, 20 Jul 2026 15:13:41 +0800 Message-Id: <20260720071342.50742-4-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20260720071342.50742-1-shikemeng@huaweicloud.com> References: <20260720071342.50742-1-shikemeng@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgAX4qKnyl1qax5+Bw--.27530S5 X-Coremail-Antispam: 1UD129KBjvdXoWrtw1Dur1rAF1rKr1UCryDZFb_yoWDGrg_Aa 48Zws7JFWYqr1kX39rta47Xr4fKr4fK3Z5WFyktFy2yry5X3y5uFnrXF1DAw48Ka10yFyf Aw1qvr17Kw47tjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUb6AFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUWwA2048vs2IY02 0Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xv wVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM2 8EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1l e2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI 8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwAC jcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7CjxVAaw2AFwI0_Jw0_GF yl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWU JVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7V AKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIx AIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VU1sYFtUUUUU= = X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ Content-Type: text/plain; charset="utf-8" Return immediately when the first non-zero swap count is found as any non-zero swap count prevents freeing extend_table and further iteration is pointless. Signed-off-by: Kemeng Shi Reviewed-by: Youngjun Park --- mm/swapfile.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 81c4040912be..3fcbd10c6353 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1530,20 +1530,17 @@ int swap_retry_table_alloc(swp_entry_t entry, gfp_t= gfp) static void swap_extend_table_try_free(struct swap_cluster_info *ci) { unsigned long i; - bool can_free =3D true; =20 if (!ci->extend_table) return; =20 for (i =3D 0; i < SWAPFILE_CLUSTER; i++) { if (ci->extend_table[i]) - can_free =3D false; + return; } =20 - if (can_free) { - kfree(ci->extend_table); - ci->extend_table =3D NULL; - } + kfree(ci->extend_table); + ci->extend_table =3D NULL; } =20 /* Decrease the swap count of one slot, without freeing it */ --=20 2.36.1 From nobody Sat Jul 25 03:05:31 2026 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 70C973B71B8 for ; 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dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.170]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4h3Wv563c4zKHMTy for ; Mon, 20 Jul 2026 15:13:05 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id E719D4056F for ; Mon, 20 Jul 2026 15:13:45 +0800 (CST) Received: from huaweicloud.com (unknown [10.166.163.161]) by APP3 (Coremail) with UTF8SMTPA id _Ch0CgAX4qKnyl1qax5+Bw--.27530S6; Mon, 20 Jul 2026 15:13:45 +0800 (CST) From: Kemeng Shi To: chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 4/4] mm, swap: Remove unneeded swap_extend_table_try_free() in swap_dup_entries_cluster() Date: Mon, 20 Jul 2026 15:13:42 +0800 Message-Id: <20260720071342.50742-5-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20260720071342.50742-1-shikemeng@huaweicloud.com> References: <20260720071342.50742-1-shikemeng@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgAX4qKnyl1qax5+Bw--.27530S6 X-Coremail-Antispam: 1UD129KBjvdXoWruw1rGrW7uF17KFyDAFWrZrb_yoWDGrX_Wa 95A34kJF45Ja1DG3s7t3WIqr4vgrZYqr15Cr1rJFnIya4UXFWrur17X3srAw1Iqa90v3s5 Ga1vvF1Sy39xGjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbDkFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAVCq3wA2048vs2 IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28E F7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr 1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE 3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2I x0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8 JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7CjxVAaw2AFwI0_Jw 0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AK xVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrx kI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v2 6F4j6r4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr 1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VU1zpBDUU UUU== X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ Content-Type: text/plain; charset="utf-8" Since commit 0475fde0f68de ("mm, swap: avoid leaving unused extend table after alloc race"), extend table is always allocated when any swap count reach MAX - 1 and is always freed when swap count decrease to MAX - 1 or MAX - 2 with cluster lock held. So the extend table will always be freed properly when decrease swap count in __swap_cluster_put_entry(). So swap_extend_table_try_free() outside of __swap_cluster_put_entry() is unneeded and can be removed. Signed-off-by: Kemeng Shi Reviewed-by: Youngjun Park --- mm/swapfile.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 3fcbd10c6353..fc9f16bc2e4e 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1732,7 +1732,6 @@ static int swap_dup_entries_cluster(struct swap_info_= struct *si, failed: while (ci_off-- > ci_start) __swap_cluster_put_entry(ci, ci_off); - swap_extend_table_try_free(ci); swap_cluster_unlock(ci); return err; } --=20 2.36.1