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 2E272C433EF for ; Sat, 12 Feb 2022 08:28:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232607AbiBLI2b (ORCPT ); Sat, 12 Feb 2022 03:28:31 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:37718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232503AbiBLI2b (ORCPT ); Sat, 12 Feb 2022 03:28:31 -0500 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA55526AF9 for ; Sat, 12 Feb 2022 00:28:27 -0800 (PST) Received: from fsav311.sakura.ne.jp (fsav311.sakura.ne.jp [153.120.85.142]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 21C8SFv8067107; Sat, 12 Feb 2022 17:28:15 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav311.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav311.sakura.ne.jp); Sat, 12 Feb 2022 17:28:15 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav311.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 21C8SE4h067104 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Sat, 12 Feb 2022 17:28:15 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: Date: Sat, 12 Feb 2022 17:28:09 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH] block: add filemap_invalidate_lock_killable() Content-Language: en-US From: Tetsuo Handa To: Christoph Hellwig Cc: Alexander Viro , Jens Axboe , linux-block@vger.kernel.org, linux-fsdevel References: <0000000000007305e805d4a9e7f9@google.com> <3392d41c-5477-118a-677f-5780f9cedf95@I-love.SAKURA.ne.jp> <8b2a61cb-4850-8bd7-3ff3-cebebefdb01b@I-love.SAKURA.ne.jp> In-Reply-To: <8b2a61cb-4850-8bd7-3ff3-cebebefdb01b@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2022/01/04 22:26, Tetsuo Handa wrote: > On 2022/01/04 16:14, Christoph Hellwig wrote: >> On Mon, Jan 03, 2022 at 07:49:11PM +0900, Tetsuo Handa wrote: >>> syzbot is reporting hung task at blkdev_fallocate() [1], for it can take >>> minutes with mapping->invalidate_lock held. Since fallocate() has to accept >>> size > MAX_RW_COUNT bytes, we can't predict how long it will take. Thus, >>> mitigate this problem by using killable wait where possible. >> >> Well, but that also means we want all other users of the invalidate_lock >> to be killable, as fallocate vs fallocate synchronization is probably >> not the interesting case. > > Right. But being responsive to SIGKILL is generally preferable. > > syzbot (and other syzkaller based fuzzing) is reporting many hung task reports, > but many of such reports are simply overstressing. > > We can't use killable lock wait for release operation because it is a "void" > function. But we can use killable lock wait for majority of operations which > are not "void" functions. Use of killable lock wait where possible can improve > situation. > If there is no alternative, can we apply this patch?