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[209.85.128.54]) by smtp.gmail.com with ESMTPSA id jw16-20020a170906e95000b00726298147b1sm1861148ejb.161.2022.08.05.12.16.30 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Aug 2022 12:16:31 -0700 (PDT) Received: by mail-wm1-f54.google.com with SMTP id h34-20020a05600c49a200b003a5165eae0fso1661263wmp.4 for ; Fri, 05 Aug 2022 12:16:30 -0700 (PDT) X-Received: by 2002:a05:600c:5102:b0:3a5:15c9:16d3 with SMTP id o2-20020a05600c510200b003a515c916d3mr4691282wms.93.1659726990158; Fri, 05 Aug 2022 12:16:30 -0700 (PDT) MIME-Version: 1.0 References: <20211116012912.723980-1-longman@redhat.com> <20220719104104.1634-1-hdanton@sina.com> <20220722115510.2101-1-hdanton@sina.com> <20220723001713.2156-1-hdanton@sina.com> <2fcf84e6-168b-4ee7-bc9e-5b1c3c9a3d4e@redhat.com> In-Reply-To: <2fcf84e6-168b-4ee7-bc9e-5b1c3c9a3d4e@redhat.com> From: Doug Anderson Date: Fri, 5 Aug 2022 12:16:18 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5] locking/rwsem: Make handoff bit handling more consistent To: Waiman Long Cc: Hillf Danton , Peter Zijlstra , Will Deacon , Davidlohr Bueso , MM , LKML Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659726995; a=rsa-sha256; cv=none; b=aj3dBLCzN50pyXafB4y1yNo/gW3pVt6hHHqZiX0nca4ZDqhlmQzD3fArJO2Tt7OWvBfY+C IhXk4scmJtY7GHSoFjTsdJW4AHYs/DexMGPblOdsbgOHCgmJUeeAS4j9CxBhwUU2rcbYQQ R24KZoNI5sw+oyCRskFwj+MS2TJUBto= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=doGf+B4t; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf05.hostedemail.com: domain of dianders@chromium.org designates 209.85.208.51 as permitted sender) smtp.mailfrom=dianders@chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659726995; 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=21FAPNKk7R7dtwD16dK5hF3eWna1JT0Lifx6z6IAhts=; b=1CO03Kg4uJe0hiQ4BYHDQX8BG6IEuPr72byoSyeNtkAo+oOOajr5gKTQIzFPSUos7jnRBE xvksvgnrDDNDKaDgc4gv3PaEgZvH3sPpUhjtfTrKlZ3MP3YDNMeXBtc2VIrtVz6+ymNzy6 7P6iIiR0rOcIkftOlp4ndieJvRrh8yA= X-Stat-Signature: k8qa7wfb1xy3a1uywbawxokb6bu9847i X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 528F7100141 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=doGf+B4t; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf05.hostedemail.com: domain of dianders@chromium.org designates 209.85.208.51 as permitted sender) smtp.mailfrom=dianders@chromium.org X-Rspam-User: X-HE-Tag: 1659726994-125477 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: Hi, On Fri, Aug 5, 2022 at 12:02 PM Waiman Long wrote: > > > On 8/5/22 13:14, Doug Anderson wrote: > > Hi, > > > > On Fri, Jul 22, 2022 at 5:17 PM Hillf Danton wrote: > >> On Fri, 22 Jul 2022 07:02:42 -0700 Doug Anderson wrote: > >>> Thanks! I added this diff to your previous diff and my simple test > >>> still passes and I don't see your WARN_ON triggered. > >> Thanks! > >>> How do we move forward? Are you going to officially submit a patch > >>> with both of your diffs squashed together? Are we waiting for > >>> additional review from someone? > >> Given it is not unusual for us to miss anything important, lets take > >> a RWSEM_WAIT_TIMEOUT nap now or two. > > It appears that another fix has landed in the meantime. Commit > > 6eebd5fb2083 ("locking/rwsem: Allow slowpath writer to ignore handoff > > bit if not set by first waiter"). > > > > ...unfortunately with that patch my test cases still hangs. :( > > The aim of commit 6eebd5fb2083 ("locking/rwsem: Allow slowpath writer to > ignore handoff bit if not set by first waiter") is to restore slowpath > writer behavior to be the same as before commit d257cc8cb8d5 > ("locking/rwsem: Make handoff bit handling more consistent"). Ah, OK. I just saw another fix to the same commit and assumed that perhaps it was intended to address the same issue. > If the hang still exists, there may be other cause for it. Could you > share more information about what the test case is doing and any kernel > splat that you have? It's all described in my earlier reply including my full test case: https://lore.kernel.org/r/CAD=FV=URCo5xv3k3jWbxV1uRkUU5k6bcnuB1puZhxayEyVc6-A@mail.gmail.com Previously I tested Hillf's patches and they fixed it for me. -Doug