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 36220C38159 for ; Thu, 19 Jan 2023 01:48:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229819AbjASBsR (ORCPT ); Wed, 18 Jan 2023 20:48:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229841AbjASBpl (ORCPT ); Wed, 18 Jan 2023 20:45:41 -0500 Received: from lgeamrelo11.lge.com (lgeamrelo11.lge.com [156.147.23.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 11FB86CCCA for ; Wed, 18 Jan 2023 17:38:47 -0800 (PST) Received: from unknown (HELO lgemrelse7q.lge.com) (156.147.1.151) by 156.147.23.51 with ESMTP; 19 Jan 2023 10:38:46 +0900 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO localhost.localdomain) (10.177.244.38) by 156.147.1.151 with ESMTP; 19 Jan 2023 10:38:46 +0900 X-Original-SENDERIP: 10.177.244.38 X-Original-MAILFROM: byungchul.park@lge.com From: Byungchul Park To: hdanton@sina.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, longman@redhat.com, penguin-kernel@I-love.SAKURA.ne.jp, max.byungchul.park@gmail.com Subject: Re: [PATCH RFC v7 08/23] dept: Apply sdt_might_sleep_strong() to PG_{locked,writeback} wait Date: Thu, 19 Jan 2023 10:38:34 +0900 Message-Id: <1674092314-16409-1-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <20230109113720.221-1-hdanton@sina.com> References: <20230109113720.221-1-hdanton@sina.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hillf wrote: > On 9 Jan 2023 12:33:36 +0900 Byungchul Park >> Makes Dept able to track dependencies by PG_{locked,writeback} waits. >> >> Signed-off-by: Byungchul Park >> --- > > Hey Byungchul +cc max.byungchul.park@gmail.com Hi, This email never reached to me. > Is DEPT able to get deadlock reported for the syzbot report [1]? DEPT can detect the case 100% *IF* the folio_trylock() is released within the same context since DEPT tracks folio_trylock(), folio_lock() and folio_unlock(), and it's definitely a deadlock. But as we know, because folio_trylock() can be released by another context like irq, it might be either just a severe slowdown of the context triggering folio_unlock() or a literal deadlock where the context is involved. I dunno which one is the case. In short, DEPT can detect this case too *IF* it's a literal deadlock, but it doesn't if it's just a slowdown. I'm planning to warn it even if there is a slowdown tho, not for now. Let me reproduce the following issue. I will share the result. > Hillf > > [1] https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SAKURA.ne.jp/ Byungchul