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[209.85.208.180]) by smtp.gmail.com with ESMTPSA id g19sm294270lfd.28.2020.07.22.17.23.19 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-f180.google.com with SMTP id e8so4505399ljb.0 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" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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