From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5CDDC433EF for ; Mon, 13 Jun 2022 10:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243203AbiFMKWH (ORCPT ); Mon, 13 Jun 2022 06:22:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242893AbiFMKUl (ORCPT ); Mon, 13 Jun 2022 06:20:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54A371EC69; Mon, 13 Jun 2022 03:17:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C7652B80E2D; Mon, 13 Jun 2022 10:17:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B1E0C34114; Mon, 13 Jun 2022 10:17:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655115431; bh=4CnfZTVIakF7H6BgXbf61/Vv64C1smXXvBhssH3OVKs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rh0BFQlEReYcOKkJmTtMBzpw2oiQZftU4Ae6QUNrWckSykhAnRPS1gw/5djvc13wc 06FIxG6llEyS10r7Ibq5q+A3yTr2gopeVGOYceLU8J/zplYhRSQTkwz3Bd7N/K7SNg pv3BfarjLVwNHSWgQPmFAQzHH+mI6hsOUkjph3Hg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Aring , David Teigland Subject: [PATCH 4.9 082/167] dlm: fix missing lkb refcount handling Date: Mon, 13 Jun 2022 12:09:16 +0200 Message-Id: <20220613094900.120461254@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094840.720778945@linuxfoundation.org> References: <20220613094840.720778945@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Aring commit 1689c169134f4b5a39156122d799b7dca76d8ddb upstream. We always call hold_lkb(lkb) if we increment lkb->lkb_wait_count. So, we always need to call unhold_lkb(lkb) if we decrement lkb->lkb_wait_count. This patch will add missing unhold_lkb(lkb) if we decrement lkb->lkb_wait_count. In case of setting lkb->lkb_wait_count to zero we need to countdown until reaching zero and call unhold_lkb(lkb). The waiters list unhold_lkb(lkb) can be removed because it's done for the last lkb_wait_count decrement iteration as it's done in _remove_from_waiters(). This issue was discovered by a dlm gfs2 test case which use excessively dlm_unlock(LKF_CANCEL) feature. Probably the lkb->lkb_wait_count value never reached above 1 if this feature isn't used and so it was not discovered before. The testcase ended in a rsb on the rsb keep data structure with a refcount of 1 but no lkb was associated with it, which is itself an invalid behaviour. A side effect of that was a condition in which the dlm was sending remove messages in a looping behaviour. With this patch that has not been reproduced. Cc: stable@vger.kernel.org Signed-off-by: Alexander Aring Signed-off-by: David Teigland Signed-off-by: Greg Kroah-Hartman --- fs/dlm/lock.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/dlm/lock.c +++ b/fs/dlm/lock.c @@ -1555,6 +1555,7 @@ static int _remove_from_waiters(struct d lkb->lkb_wait_type = 0; lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL; lkb->lkb_wait_count--; + unhold_lkb(lkb); goto out_del; } @@ -1581,6 +1582,7 @@ static int _remove_from_waiters(struct d log_error(ls, "remwait error %x reply %d wait_type %d overlap", lkb->lkb_id, mstype, lkb->lkb_wait_type); lkb->lkb_wait_count--; + unhold_lkb(lkb); lkb->lkb_wait_type = 0; } @@ -5314,11 +5316,16 @@ int dlm_recover_waiters_post(struct dlm_ lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK; lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL; lkb->lkb_wait_type = 0; - lkb->lkb_wait_count = 0; + /* drop all wait_count references we still + * hold a reference for this iteration. + */ + while (lkb->lkb_wait_count) { + lkb->lkb_wait_count--; + unhold_lkb(lkb); + } mutex_lock(&ls->ls_waiters_mutex); list_del_init(&lkb->lkb_wait_reply); mutex_unlock(&ls->ls_waiters_mutex); - unhold_lkb(lkb); /* for waiters list */ if (oc || ou) { /* do an unlock or cancel instead of resending */