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Fri, 05 Aug 2022 15:02:11 -0400 X-MC-Unique: qvoksAyINU6K1nsOnUEzxg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 50F4385A586; Fri, 5 Aug 2022 19:02:11 +0000 (UTC) Received: from [10.18.17.215] (dhcp-17-215.bos.redhat.com [10.18.17.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id DAD99C27D95; Fri, 5 Aug 2022 19:02:10 +0000 (UTC) Message-ID: <2fcf84e6-168b-4ee7-bc9e-5b1c3c9a3d4e@redhat.com> Date: Fri, 5 Aug 2022 15:02:10 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v5] locking/rwsem: Make handoff bit handling more consistent Content-Language: en-US To: Doug Anderson , Hillf Danton Cc: Peter Zijlstra , Will Deacon , Davidlohr Bueso , MM , LKML 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> From: Waiman Long In-Reply-To: Content-Type: text/plain; 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bh=GIcmLgWRQIu/jzaYm/Us8pJ8sFlavYikN+PtkX6N63Y=; b=UxcpXDZlPPvrogKUynZGy3fNXKTwSHyfo2V1Sv0T6dQCqj9pCRW2pj/rWpsoyuAsZAsl5m WMRUT+cfY+zEWI4N6JbNPYSfyaaKZNJFp7wNnx5cvkRAHTxmA6Ks457O4T2eLzqrDn0RUq 4mAXfayyrKaalmrX1PtUwi8GGawUR3g= X-Stat-Signature: 7n4ejxxd6ewjjw3xfbr4uydn6q9snzpg X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 907968014F Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IbLTtwuV; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf30.hostedemail.com: domain of longman@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=longman@redhat.com X-Rspam-User: X-HE-Tag: 1659726135-907697 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 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"). 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? Thanks, Longman