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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DE9EFA3740 for ; Tue, 25 Oct 2022 19:19:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AD4758E0002; Tue, 25 Oct 2022 15:19:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A84A28E0001; Tue, 25 Oct 2022 15:19:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 973058E0002; Tue, 25 Oct 2022 15:19:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 874388E0001 for ; Tue, 25 Oct 2022 15:19:49 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 33C93140262 for ; Tue, 25 Oct 2022 19:19:49 +0000 (UTC) X-FDA: 80060436498.13.ABE5E0D Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id C5CFA8000B for ; Tue, 25 Oct 2022 19:19:47 +0000 (UTC) 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: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666725588; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=n09+bMZNLfgYM0EqQ82ZGI+GYi1rd+xN3Y3MHKhcBWg=; b=H0saLrsTKaO/JXj0s0I1guDcx4XkQRiPf733RJpM5xBGP0wkqVYYkxUGFh/9mRszd1oz/4 qWUIUd1r9qkYoLlkgcf7RWRDEb2Nq4Kbbs4OyixrvOhXN/zA4dG8rKnCcMxJRoPaEGJGY4 yd+dNqLcyEqK9WSOrx8tcMaF97s9oSA= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=CP6yoRqX; dmarc=none; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666725588; a=rsa-sha256; cv=none; b=qmNOTUrCdG0hbz3BqdijxeMNaABiDS+x5/7CmhcjSLNTSRxabCRbqrDRnrF3pu+YX3MtRT JdbcQE6eqArwgLCSZwBNWdsi2T7Nt1SR26Z9kToFdRL9CrdcFMQOD2N11RsqflAh1zVouf enTf9LlW9nkfLo8xrIRiiowLVbsqCbw= X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C5CFA8000B X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=CP6yoRqX; dmarc=none; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Stat-Signature: jiazyz1nnkug8itzuujg1bbirktd3bj6 X-HE-Tag: 1666725587-999939 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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?