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Thu, 10 Apr 2025 05:32:11 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG5qEzKDpLVJLqsXJE+8XQz5tr9maYCR/qX4nyYZq9YvKO8WnRM8qNCTY7QXBulOSKkB39xDg== X-Received: by 2002:a05:6a21:99a9:b0:1fd:e9c8:b8c3 with SMTP id adf61e73a8af0-2016ce05c7emr2787694637.26.1744288330786; Thu, 10 Apr 2025 05:32:10 -0700 (PDT) Received: from [192.168.68.55] ([180.233.125.65]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-73bb1e694e0sm3213317b3a.170.2025.04.10.05.32.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Apr 2025 05:32:10 -0700 (PDT) Message-ID: <0b4b56fa-a04f-455d-aeb0-97c065c3ec05@redhat.com> Date: Thu, 10 Apr 2025 22:32:04 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REPORT] Softlockups on PowerNV with upstream To: Aditya Gupta Cc: Oscar Salvador , linux-mm@kvack.org, Andrew Morton , Danilo Krummrich , David Hildenbrand , Greg Kroah-Hartman , Mahesh J Salgaonkar , "Rafael J. Wysocki" , Sourabh Jain , linux-kernel@vger.kernel.org, Donet Tom , Gavin Shan References: <20250409180344.477916-1-adityag@linux.ibm.com> <675d6580-814f-4fae-9dc5-9470645adc07@redhat.com> From: Gavin Shan In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: zr73lNgAaAF7P8GAqsfn_8gNM08D6ZP0Ii5SfRsnNks_1744288331 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: DDB71A0012 X-Stat-Signature: kfmcmmcbtp8scqytdha8763w9g9h7q66 X-HE-Tag: 1744288333-505419 X-HE-Meta: U2FsdGVkX1/n/VqXfgyy1+D3uhAHwL25t0koJkLTUQOvBGgNvUnNBJJ3nlcfXrhHiwJXQLplwkybeaHIXIcZ3/Cb3CsHQPXVJVIxfOOaeGqEzG9+sVFp1kpWPdGD4X7wKIUK9i71UUg2QJX2tATyefaEmXyeSRXQ3b6sZ4T295nGVUuD/k3mlIcm6yNCrz0GOqcEofU/y4Y5fWunCoEKoyQI/s2afQfv9f2TeV5i3gOep/lVg5HrCQy7KUjAY68QxY2QyzSUh/N5TkROE69c6eHrva14EC49o0OQX3qPeCFM8HI1+HrFI/XTGQ7PGy0fWw+qE6POPgmGIge0A2+pl4bG+RohuDM7+7YYB+ur+tKdeIVQexylXUD5md3cEz4vSF3mCVXGugsAeKWpov2v1cj+ihsvQ3LOYFTW8h5ctxm1gLhbbb0m3l3WKr6xpmHvBMmDSDuEUzcUcorS2Nf7EPWXFHaa7cdbDktg5fhVWrvIFMBzX8jQsjcg0Z/eEmFafjfuPCy1Kr1UM107zRkl2EhXTtJaFE/KfMsgBHI7XtxslRoB6OWQUpIvFGFi34D/VV0kJotf/qkqzjhI12NMp38wk+I3LXTgL2kKXuoHq1TWg7GXh24Qhi40bnffDCHJwwVLz3o8rb1omEzKa7bUkHxR1qHYGBqYQlBtPRcszWfdLnlOHdhDvpq8FnNV4Er5eYlBtIijDDOpp1BwtaPG1kYrRequXgrutHJSwQ0wHD5axfIkjmmzG15xw/qwTIGU+6kEjs1LLM9aEZ8DgmjfcRqlodiMbDvlQFTc5kE5TJhaxSIU+U/ER3Q12CRPuKSHj1yc1Pq4NgZrzZYS12nWJ0jDX16lNbcY2C5m7gOmqzJ4K9OWrLBqnJzXvOLynckaWpb7ax4cxZszFkjX4hGn0VrKW/4+5GvJPuJUTZJRibKi/lqO41OBtYyLvo24H+mjYOukpmiJ+YQTvH5Z5Sn 0e2IiqXu crhfxudPCmvdDuN6ygAfkaDoVbrN7scyv7CZaKbaph8fy2uTDpHXFWKE5jC7TtRy+Iks50yrR/U9Epj5UTMBWusz0AtfSlFbzbqhLBHdgmgsOYOxqcs2w8nEu2ozBN2dw3XMocxhfxK7Uf9qs0kkopcHZrXEBOU/gsgFelsiIxDnWQgdW5ZVxgVVO3P+3k+3tuHe7H2jhFRmSHQ1KgtYX0woBJ4ny/bRowexp2k0cqsmhmLX7oRFxQvDjZl+gyKC+MoZ3f29EuqeiPN6nZsn5cQzi5NijI68nHNLLz1ZnSr252NITQdL3wO4t55RXX130uZlK9HHBETYm/CWNFo3pqlM4ugnJAbBMbiVCFmbs1NfXd6FIa7lEDYSjfRqkVdgI03NGFKKuqwQz/6TrUsHXaxyXHOZm5v32p51ShOaYxHSoCLkK+t3R5/6bJ30j2iaLo+VwvpXCSJlfQqA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.337845, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/10/25 10:22 PM, Aditya Gupta wrote: > Cc +donet > > On 25/04/10 07:44PM, Gavin Shan wrote: >> On 4/10/25 6:23 PM, Oscar Salvador wrote: >>> On Thu, Apr 10, 2025 at 03:35:19PM +1000, Gavin Shan wrote: >>>> Thanks, Oscar. You're correct that the overhead is introduced by for_each_present_section_nr(). >>>> I already had the fix, working on IBM's Power9 machine, where the issue can be >>>> reproduced. Please see the attached patch. >>>> >>>> I'm having most tests on ARM64 machine for the fix. >>> >>> Looks good to me. >>> But we need a comment explaining why block_id is set to ULONG_MAX >>> at the beginning as this might not be obvious. >>> >>> Also, do we need >>> if (block_id != ULONG_MAX && memory_block_id(nr) == block_id) ? >>> >>> Cannot just be >>> >>> if (memory_block_id(nr) == block_id) ? >>> >>> AFAICS, the first time we loop through 'memory_block_id(nr) == ULONG_MAX' >>> will evaluate false and and we will set block_id afterwards. >>> >>> Either way looks fine to me. >>> Another way I guess would be: >>> >> >> Yeah, we need to record the last handled block ID by @block_id. For the >> first time to register the block memory device in the loop, @block_id needs >> to be invalid (ULONG_MAX), bypassing the check of 'memory_block_id(nr) == block_id'. >> I will post the fix for review after Aditya confirms it works for him, with extra >> comment to explain why @block_id is initialized to ULONG_MAX. >> >> Aditya, please have a try when you get a chance, thanks! I verified it on Power9 >> machine where the issue exists and on one of my ARM64 machine. > > I don't see any softlockups now with your patch as well as Oscar's patch. > > Tested on PowerNV Power10. > > Thanks for the quick replies Gavin. Nice, thanks for the quick test, Aditya. I will send the fix for reivew, with you copied. Thanks, Gavin