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 81040C38A2D for ; Tue, 25 Oct 2022 19:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232151AbiJYTT4 (ORCPT ); Tue, 25 Oct 2022 15:19:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231374AbiJYTTy (ORCPT ); Tue, 25 Oct 2022 15:19:54 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2B6425E8C; Tue, 25 Oct 2022 12:19:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=n09+bMZNLfgYM0EqQ82ZGI+GYi1rd+xN3Y3MHKhcBWg=; b=CP6yoRqXwLlL65ib2h5kbr48BI 8OnBVUhz3p1Vo36458CKULWEjbB0MwXMT1VEInqNiwhPuPfE7sXaRFhtjl82aJrchUhVYEdMcxjCq 9SbkuQwR/A8NQ83doZ4y2MxPoatpEajlH+3gkgPExCidirm5PFmy/OeuwFKmOM1X17oYEsSMWanIu MBON3DyX/VSZW4zhgJ54sI5IXWbR7VXI8FGrWlRLsCxdaQX00j5wJL9p2JNXPxEga4xtJiYahtIVp 3R6VerrsjmFBh8zsg1/45fjX9guGzZzFWEJbjpi6G8zIIiHRhy6H2nHFhp66te9vdmiGgihA+JJNz Mh/+wJAw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1onPSi-00GUEW-JD; Tue, 25 Oct 2022 19:19:44 +0000 Date: Tue, 25 Oct 2022 20:19:44 +0100 From: Matthew Wilcox To: Linus Torvalds Cc: Dan Williams , Brian Foster , Linux-MM , linux-fsdevel , linux-xfs , Hugh Dickins , jesus.a.arechiga.lopez@intel.com, tim.c.chen@linux.intel.com Subject: Re: writeback completion soft lockup BUG in folio_wake_bit() Message-ID: References: <6350a5f07bae2_6be12944c@dwillia2-xfh.jf.intel.com.notmuch> <6356f1f74678c_141929415@dwillia2-mobl3.amr.corp.intel.com.notmuch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Oct 24, 2022 at 01:28:31PM -0700, Linus Torvalds wrote: > It does sound like we now very much have hard data for "the page > waitlist complexity is now a bigger problem than the historical > problem it tried to solve". > > So I'll happily apply it. The only question is whether it's a "let's > do this for 6.2", or if it's something that we'd want to back-port > anyway, and might as well apply sooner rather than later as a fix. > > I think that in turn then depends on just how artificial the test case > was. If the test case was triggered by somebody seeing problems in > real life loads, that would make the urgency a lot higher. But if it > was purely a synthetic test case with no accompanying "this is what > made us look at this" problem, it might be a 6.2 thing. > > Arechiga? > > Also, considering that Willy authored the patch (even if it's really > just a "remove this whole code logic"), maybe he has opinions? Willy? I've been carrying a pair of patches in my tree to rip out the wait bookmarks since March, waiting for me to write a userspace testcase to reproduce the problem against v4.13 and then check it no longer does so against v5.0. Unfortunately, that hasn't happened. I'm happy to add Arechiga's Tested-by, and submit them to Andrew and have him bring them into v6.2, since this doesn't seem urgent?