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 9D334171A9 for ; Mon, 22 May 2023 19:26:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02E29C433D2; Mon, 22 May 2023 19:26:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684783593; bh=UitNJATXfwLU//5VZHJZ1rqVgYxAGa2r5kH97N86JqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K8hEUdJMsUOa3MoQniNNH4XhLIKvUuDh3fWL3VIUuOuqarTHQidklT5B9JMetSb39 J7PlErpcGeEH2nzgGN3/Nhqv4MRlnZ/GwhAoX+X21SO7gmap55OIwzjHxjmGASkVQZ mpT+7Atxc+LHl2lIJkGNsb8/fw1Pja4M5SjSr3Qg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Song Liu , Sasha Levin Subject: [PATCH 6.1 097/292] md: fix soft lockup in status_resync Date: Mon, 22 May 2023 20:07:34 +0100 Message-Id: <20230522190408.396795454@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230522190405.880733338@linuxfoundation.org> References: <20230522190405.880733338@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Yu Kuai [ Upstream commit 6efddf1e32e2a264694766ca485a4f5e04ee82a7 ] status_resync() will calculate 'curr_resync - recovery_active' to show user a progress bar like following: [============>........] resync = 61.4% 'curr_resync' and 'recovery_active' is updated in md_do_sync(), and status_resync() can read them concurrently, hence it's possible that 'curr_resync - recovery_active' can overflow to a huge number. In this case status_resync() will be stuck in the loop to print a large amount of '=', which will end up soft lockup. Fix the problem by setting 'resync' to MD_RESYNC_ACTIVE in this case, this way resync in progress will be reported to user. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230310073855.1337560-3-yukuai1@huaweicloud.com Signed-off-by: Sasha Levin --- drivers/md/md.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index d5c362b1602b6..bb73a541bb193 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8028,16 +8028,16 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev) } else if (resync > max_sectors) { resync = max_sectors; } else { - resync -= atomic_read(&mddev->recovery_active); - if (resync < MD_RESYNC_ACTIVE) { - /* - * Resync has started, but the subtraction has - * yielded one of the special values. Force it - * to active to ensure the status reports an - * active resync. - */ + res = atomic_read(&mddev->recovery_active); + /* + * Resync has started, but the subtraction has overflowed or + * yielded one of the special values. Force it to active to + * ensure the status reports an active resync. + */ + if (resync < res || resync - res < MD_RESYNC_ACTIVE) resync = MD_RESYNC_ACTIVE; - } + else + resync -= res; } if (resync == MD_RESYNC_NONE) { -- 2.39.2