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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CFD02C433E4 for ; Thu, 23 Jul 2020 00:23:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8E70C20825 for ; Thu, 23 Jul 2020 00:23:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="faikLq+G" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E70C20825 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 130906B0002; Wed, 22 Jul 2020 20:23:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0BA6A6B0005; Wed, 22 Jul 2020 20:23:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EC46D6B0006; Wed, 22 Jul 2020 20:23:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id D30BA6B0002 for ; Wed, 22 Jul 2020 20:23:23 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 80A7B2EEB83 for ; Thu, 23 Jul 2020 00:23:23 +0000 (UTC) X-FDA: 77067441486.23.ink14_5313e6426f3a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 4ABA33848F for ; Thu, 23 Jul 2020 00:23:23 +0000 (UTC) X-HE-Tag: ink14_5313e6426f3a X-Filterd-Recvd-Size: 4801 Received: from mail-lj1-f194.google.com (mail-lj1-f194.google.com [209.85.208.194]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Thu, 23 Jul 2020 00:23:22 +0000 (UTC) Received: by mail-lj1-f194.google.com with SMTP id h22so4465335lji.9 for ; Wed, 22 Jul 2020 17:23:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MLLzW+27c7XskPvxXHpuyTEdYRgvVTLDhxahIBegs8U=; b=faikLq+G0vsoBxFYA9T/K3S7QiQTxZoo+WHfXFKRntEclWn6SyFd0s8e5ihC2YGfEC xwEvgtLDOzsUvG+mLwzkpkw5BWy4EaMb85BSL5WQahdJG+1+X8n95u66NxFu9yT0IBOw 4tNBH4IclDxdU2pXAz9akDwoOAVeAIioMO1QA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MLLzW+27c7XskPvxXHpuyTEdYRgvVTLDhxahIBegs8U=; b=cV/f4kJoCcsfSYKAfbqdqHzAzSeofIBvkpPPfaWLaQoje68UIg2cXtJdOKeh98POSh eWF9WXzOaUljt54mA5tGYtTqh0L09K1efef8JpXz64JMO7R9kSL5a4gG7M8kTP4yXwVj bsmRlSar1dCwZ2fG7ipAsmLPvPn3O7j98nz4w6Ghbx1DUr7YvVS8TU925xcsBX17C6Xg jJjLDLyICUaByg75F9y4nFvIXx6pACE5PyN/ryxv2D7y/Nvujtcnu6lbLXvuuoFxjXSI gWNi7YEe/y/uIXkbadtLJSCxylWLOTKL576rqM8k7+qH4wvIyt/2PxsmNxquioH0SHWP fLjQ== X-Gm-Message-State: AOAM533NHWOoGu4eLp2u5Gi/65n5T7qKO/R1/PgkiBKl/GkJtgx5sJrD meO1JkDMZRkAePvzItl1AsSkvi+6AHE= X-Google-Smtp-Source: ABdhPJw7B/EKY3G8atJkETWHq5EkWeorLW08IAqSlbzbrLMCmLDM/ySSK9DWFV0Q1leChNG/i9UC/A== X-Received: by 2002:a05:651c:1053:: with SMTP id x19mr688362ljm.396.1595463800789; Wed, 22 Jul 2020 17:23:20 -0700 (PDT) Received: from mail-lj1-f175.google.com (mail-lj1-f175.google.com. [209.85.208.175]) by smtp.gmail.com with ESMTPSA id f5sm1243715lja.17.2020.07.22.17.23.19 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Jul 2020 17:23:19 -0700 (PDT) Received: by mail-lj1-f175.google.com with SMTP id q6so4479050ljp.4 for ; Wed, 22 Jul 2020 17:23:19 -0700 (PDT) X-Received: by 2002:a2e:9c92:: with SMTP id x18mr706723lji.70.1595463798932; Wed, 22 Jul 2020 17:23:18 -0700 (PDT) MIME-Version: 1.0 References: <20200721063258.17140-1-mhocko@kernel.org> In-Reply-To: From: Linus Torvalds Date: Wed, 22 Jul 2020 17:23:03 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH] mm: silence soft lockups from unlock_page To: Hugh Dickins , Oleg Nesterov Cc: Michal Hocko , Linux-MM , LKML , Andrew Morton , Tim Chen , Michal Hocko Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 4ABA33848F X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Wed, Jul 22, 2020 at 4:42 PM Linus Torvalds wrote: > > NOTE NOTE NOTE! This is both somewhat subtle code, and ENTIRELY > UNTESTED. It seems to boot. It adds more lines than it removes, but a lot of it is comments, and while it's somewhat subtle, I think it's actually conceptually simpler than what we had before. The actual waiting loop itself, for example, is now entirely and utterly trivial. The DROP behavior is also a lot more straightforward and logical, imnsho. The biggest annoyance I have with it is how it open-codes "finish_wait()", and honestly, the "proper" fix for that would likely be to simply instead make "finish_wait()" return the "did I need to remove it from the list or not" value. That's the only reason that patch open-codes it right now. It _feels_ like the right solution to this thing. But maybe that's just the "pee in the snow" effect, where I like it only because I've put my mark on it. So it would be good to get more opinions, and perhaps more testing than my limited "it boots and works for me, and I can still build kernels and run a browser". Linus