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 8A8E7C3527A for ; Tue, 5 Apr 2022 12:02:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1381888AbiDEL75 (ORCPT ); Tue, 5 Apr 2022 07:59:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243323AbiDEIuV (ORCPT ); Tue, 5 Apr 2022 04:50:21 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BFB913D35; Tue, 5 Apr 2022 01:38:38 -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 4FD54B81BBF; Tue, 5 Apr 2022 08:38:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1E43C385A2; Tue, 5 Apr 2022 08:38:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649147917; bh=FUcnqxzjXH5u3vbw4nDqrygn9TouK/7YERh2EEo0v3w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hZ9KVrrS8pTFxDNNc5Q65OIpjrwYAB8d18F3eEpK+sHKicqm5LY0EihkZzJ1UDiar 7XViUCsZKb7TCbysWjdAaEaglZftF4nJHldTCDT1mIU1RG8qorxKvX6BVlPj2+kYt4 8wKwc/STja53WA7WF3ZpkZgH9SV9ywjmigvYV0H8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mingzhe Zou , Coly Li Subject: [PATCH 5.16 0169/1017] bcache: fixup multiple threads crash Date: Tue, 5 Apr 2022 09:18:02 +0200 Message-Id: <20220405070359.242350780@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@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: Mingzhe Zou commit 887554ab96588de2917b6c8c73e552da082e5368 upstream. When multiple threads to check btree nodes in parallel, the main thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag: wait_event_interruptible(check_state->wait, atomic_read(&check_state->started) == 0 || test_bit(CACHE_SET_IO_DISABLE, &c->flags)); However, the bch_btree_node_read and bch_btree_node_read_done maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE will be set. If the flag already set, the main thread return error. At the same time, maybe some threads still running and read NULL pointer, the kernel will crash. This patch change the event wait condition, the main thread must wait for all threads to stop. Fixes: 8e7102273f597 ("bcache: make bch_btree_check() to be multithreaded") Signed-off-by: Mingzhe Zou Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Coly Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/bcache/btree.c | 6 ++++-- drivers/md/bcache/writeback.c | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-) --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -2060,9 +2060,11 @@ int bch_btree_check(struct cache_set *c) } } + /* + * Must wait for all threads to stop. + */ wait_event_interruptible(check_state->wait, - atomic_read(&check_state->started) == 0 || - test_bit(CACHE_SET_IO_DISABLE, &c->flags)); + atomic_read(&check_state->started) == 0); for (i = 0; i < check_state->total_threads; i++) { if (check_state->infos[i].result) { --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -998,9 +998,11 @@ void bch_sectors_dirty_init(struct bcach } } + /* + * Must wait for all threads to stop. + */ wait_event_interruptible(state->wait, - atomic_read(&state->started) == 0 || - test_bit(CACHE_SET_IO_DISABLE, &c->flags)); + atomic_read(&state->started) == 0); out: kfree(state);