From nobody Sat Jul 25 23:41:46 2026 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6FBD82D0602; Sat, 11 Jul 2026 14:23:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783779825; cv=none; b=hogUO0rA/fn2VwhNAr162wixXH7kUfZ3qJYai5WRDrTopVEoq2tacXW9czScyNqS5y48o4yxwBFs8+z9r2XfzN9BrdlEj60GtaE/MLNtuODm0A7dYd+ntgpZQrqK6CRlaGmyw6QmEkig8ohW0t9MnpR22v/LcyBM1TS5CiCfohM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783779825; c=relaxed/simple; bh=qx7DtuNcw6rOQv9dA98LzpNw872X413+KqH9LTc4PEk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Ts/wJaj/MkbtXSFy4c4mJE/0kBbLRkDt0EbTqIy/RcHUJoOY52ZpbSiYwUtwY6LSLwjn6jDSHPqo28TMMcfTGGjoS0HKOK2Sjq7nZiBPOtcu3hfa7jNhBCLWbiziC8s5QbB4NijlELSd9UkZKyqRAxPUXaS7WeFXVa7a/LrZ9Vc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from DESKTOP-L0HPE2S.localdomain (unknown [111.199.64.102]) by APP-01 (Coremail) with SMTP id qwCowAAHn8fiUVJqyQGFBQ--.27760S2; Sat, 11 Jul 2026 22:23:30 +0800 (CST) From: Haotian Zhang To: agk@redhat.com, snitzer@kernel.org, mpatocka@redhat.com, bmarzins@redhat.com Cc: dm-devel@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Haotian Zhang Subject: [PATCH] dm-switch: use WRITE_ONCE() in switch_region_table_write() Date: Sat, 11 Jul 2026 22:21:55 +0800 Message-ID: <20260711142155.20727-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.43.0 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: qwCowAAHn8fiUVJqyQGFBQ--.27760S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Xw17Jr1kKFy7KFW3Xry5urg_yoW8JF1Upa 4rtryY9FWaqF13Z3WUGa1q9as5Cw47KFyUCr47Ga40va48Xry5JFW8Xa4aqFn8AFWxJ3W5 XrWUtr1rGw4rJa7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkG14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r4j6ryUM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_Cr1j6rxdM28EF7xvwVC2z280aVCY1x0267AKxVWxJr 0_GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7CjxVAaw2AFwI0_ JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67 AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIY rxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14 v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUBVbkUUU UU= X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiDAAFA2pSUF4CPAAAsC Content-Type: text/plain; charset="utf-8" switch_region_table_read() accesses the region table with READ_ONCE() and is called from the lockless switch_map() IO path. However, switch_region_table_write() stores to the same array with a plain assignment. This results in an inconsistent access pattern for a lockless shared variable and may trigger data race reports. Use WRITE_ONCE() to pair with the existing READ_ONCE() in switch_region_table_read(). Cc: stable@vger.kernel.org Fixes: 99eb1908e643 ("dm switch: factor out switch_region_table_read") Signed-off-by: Haotian Zhang --- drivers/md/dm-switch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c index 5952f02de1e6..e5b507b4fa7b 100644 --- a/drivers/md/dm-switch.c +++ b/drivers/md/dm-switch.c @@ -184,7 +184,7 @@ static void switch_region_table_write(struct switch_ctx= *sctx, unsigned long reg pte =3D sctx->region_table[region_index]; pte &=3D ~((((region_table_slot_t)1 << sctx->region_table_entry_bits) - 1= ) << bit); pte |=3D (region_table_slot_t)value << bit; - sctx->region_table[region_index] =3D pte; + WRITE_ONCE(sctx->region_table[region_index], pte); } =20 /* --=20 2.25.1