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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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: EBE151F38C X-Spam-Score: -4.51 X-Rspamd-Action: no action X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; TO_DN_SOME(0.00)[]; RCPT_COUNT_SEVEN(0.00)[11]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; ASN(0.00)[asn:25478, ipnet:::/0, country:RU]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Level: 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