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Thu, 10 Apr 2025 08:23:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id w5TmEPt/92cTCAAAD6G6ig (envelope-from ); Thu, 10 Apr 2025 08:23:23 +0000 Date: Thu, 10 Apr 2025 10:23:13 +0200 From: Oscar Salvador To: Gavin Shan Cc: Aditya Gupta , 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 Subject: Re: [REPORT] Softlockups on PowerNV with upstream Message-ID: References: <20250409180344.477916-1-adityag@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 68F51100009 X-Stat-Signature: hu8xphp7hrump179krcwq3fmtxz7qm67 X-HE-Tag: 1744273405-640592 X-HE-Meta: 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 bu4Z/ok1 FfEb9NK9ftljHuMa+TCRiVxpdzymC0JfGoIlO+Xw9OPljAz4MgidLRQAY93fJbf0Zr7McZr6I2wWLs9t8nGcgxIGk1eV4sJYlVTFBgsms3NOBqFJ/J0pS0R/trtr2PBUdE4GsqIjGMsQlhJ+qvE18otIw4+eCh1EMSgdQOkGr0lOEFV1udXbYb8B++cTIK5v84Li4Ml6WJE9gDM/ZU0jHwLPmexMI/AadAWQB3j9yoBe9IohgWnxr0l6TfSOzAskJYRhdQmxdx4N0JBk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.031758, 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 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: -- Oscar Salvador SUSE Labs