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Mon, 19 Feb 2024 14:20:17 +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 kZ55FqFj02UMXwAAD6G6ig (envelope-from ); Mon, 19 Feb 2024 14:20:17 +0000 Date: Mon, 19 Feb 2024 15:20:08 +0100 From: Michal Hocko To: Donet Tom Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Aneesh Kumar , Huang Ying , Dave Hansen , Mel Gorman , Ben Widawsky , Feng Tang , Andrea Arcangeli , Peter Zijlstra , Ingo Molnar , Rik van Riel , Johannes Weiner , Matthew Wilcox , Mike Kravetz , Vlastimil Babka , Dan Williams , Hugh Dickins , Kefeng Wang , Suren Baghdasaryan Subject: Re: [PATCH 3/3] mm/numa_balancing:Allow migrate on protnone reference with MPOL_PREFERRED_MANY policy Message-ID: References: <9c3f7b743477560d1c5b12b8c111a584a2cc92ee.1708097962.git.donettom@linux.ibm.com> <8d7737208bd24e754dc7a538a3f7f02de84f1f72.1708097962.git.donettom@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: <8d7737208bd24e754dc7a538a3f7f02de84f1f72.1708097962.git.donettom@linux.ibm.com> Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b="D3jmGX/h" X-Spamd-Result: default: False [0.14 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; DKIM_TRACE(0.00)[suse.com:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_TWELVE(0.00)[22]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-0.05)[59.54%] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Score: 0.14 X-Rspamd-Queue-Id: 933891F804 X-Spam-Level: X-Spam-Flag: NO X-Spamd-Bar: / On Sat 17-02-24 01:31:35, Donet Tom wrote: [...] > +static inline bool mpol_preferred_should_numa_migrate(int exec_node, int folio_node, > + struct mempolicy *pol) > +{ > + /* if the executing node is in the policy node mask, migrate */ > + if (node_isset(exec_node, pol->nodes)) > + return true; > + > + /* If the folio node is in policy node mask, don't migrate */ > + if (node_isset(folio_node, pol->nodes)) > + return false; > + /* > + * both the folio node and executing node are outside the policy nodemask, > + * migrate as normal numa fault migration. > + */ > + return true; > +} I have looked at this again and only now noticed that this doesn't really work as one would expected. case MPOL_PREFERRED_MANY: /* * use current page if in policy nodemask, * else select nearest allowed node, if any. * If no allowed nodes, use current [!misplaced]. */ if (node_isset(curnid, pol->nodes)) goto out; z = first_zones_zonelist( node_zonelist(numa_node_id(), GFP_HIGHUSER), gfp_zone(GFP_HIGHUSER), &pol->nodes); polnid = zone_to_nid(z->zone); break; Will collapse the whole MPOL_PREFERRED_MANY nodemask into the first notde into that mask. Is that really what we want here? Shouldn't we use the full nodemask as the migration target? -- Michal Hocko SUSE Labs