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b=ICJz8y+PaYc9HWNIiP4kSa067DXNL5pU4EhN5COf3/xrhN9XnHBgW89lgawARDaob yXGs0djU+69lC0tsa/ziDIEehEqwopoCfSya9L+8gWIoUZH2coPsiYHUkmvcRz5rmI RA4kdB8RxyGJ27r0+rkQ4CnJRnTaGBRt8Onk4B6FGoof0ZqJCyapAlSOOCcZila6kw Em83jgfr7+3dMfaw4GvaJE6AuLhs0U5L+moC2S5jRN5JtVsoypi3kful/E3e4VwPL3 SECH8qntp7HgeeQuQls1W/SIrBqrh0yN4ygkjoRHTY4NNdg1l75mhkwwPDkVM9x3t9 UNv7To0JvsLdg== Message-ID: <906bae9d-dcf0-463b-ac9d-81ef8cc2cc2f@kernel.org> Date: Thu, 3 Sep 2026 17:15:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm: refactor find_next_best_node to find_next_best_node_in Content-Language: en-US To: Gregory Price , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com References: <20260902215853.156267-1-gourry@gourry.net> <20260902215853.156267-2-gourry@gourry.net> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D3CEB14000E X-Stat-Signature: qxfec4p58m4pw8itj3e1rett7fc9xumj X-HE-Tag: 1788448528-406173 X-HE-Meta: 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 PXZ7qVNk e4M/KJrHOlbOkiPdoe0hXbDu/tD9F7RVMFZ0sIJOL8VlowNuRkgKqscMTaCkJC2vTgHjvdzYgWiSYLRwEzGL3cy6kYymE4D59XhhYhrt/cxO3T/EFaM9Fql4LXNqAZWEY+1baeWFyTnhzI0A0AvPHEKkwJtyor9fqw5CPuzWwi132x/Mm7bVF3JZLz75kZB4vceE/W1bARoWsJEAjGnl5vNqaVb5vVCxHctWQG+8ig0Diz82SHwKKkp4FO5iqMukWYoB85euJsPHpgAvCjQU+6U15OEDHABw9JtZevekMT4CcEzeiI9XEWboi7Mza6uEOMdJBn1bvthtrAebCNk9jKjzo9PaUqxUswA1CF7n3OI74kuzuLqE9U76A5rn1STzYl1QOgF4PmXFcM0U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/2/26 23:58, Gregory Price wrote: > find_next_best_node() picks the next-closest node for a fallback list > from the full N_MEMORY set. Refactor it into find_next_best_node_in(), > which takes an explicit candidates nodemask. > > This enables building fallback lists with non-N_MEMORY candidates. > > No functional change: every caller still selects from N_MEMORY. > > Signed-off-by: Gregory Price Reviewed-by: Vlastimil Babka (SUSE) Nit: > --- > mm/internal.h | 6 ++++-- > mm/memory-tiers.c | 7 ++++--- > mm/page_alloc.c | 13 ++++++++----- > 3 files changed, 16 insertions(+), 10 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index e16f1250b25c8..18d041ff5c52c 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -1130,7 +1130,8 @@ extern int node_reclaim_mode; > > extern unsigned long node_reclaim(struct pglist_data *pgdat, > gfp_t gfp_mask, unsigned int order); > -extern int find_next_best_node(int node, nodemask_t *used_node_mask); > +extern int find_next_best_node_in(int node, nodemask_t *used_node_mask, > + const nodemask_t *candidates); Drop the extern while touching a line. > #else > #define node_reclaim_mode 0 > > @@ -1139,7 +1140,8 @@ static inline unsigned long node_reclaim(struct pglist_data *pgdat, > { > return 0; > } > -static inline int find_next_best_node(int node, nodemask_t *used_node_mask) > +static inline int find_next_best_node_in(int node, nodemask_t *used_node_mask, > + const nodemask_t *candidates) > { > return NUMA_NO_NODE; > } > diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c > index 54851d8a195b0..25e121851b586 100644 > --- a/mm/memory-tiers.c > +++ b/mm/memory-tiers.c > @@ -370,7 +370,7 @@ int next_demotion_node(int node, const nodemask_t *allowed_mask) > * closest demotion target. > */ > nodes_complement(mask, *allowed_mask); > - return find_next_best_node(node, &mask); > + return find_next_best_node_in(node, &mask, &node_states[N_MEMORY]); > } > > static void disable_all_demotion_targets(void) > @@ -450,7 +450,7 @@ static void establish_demotion_targets(void) > memtier = list_next_entry(memtier, list); > tier_nodes = get_memtier_nodemask(memtier); > /* > - * find_next_best_node, use 'used' nodemask as a skip list. > + * find_next_best_node_in, use 'used' nodemask as a skip list. > * Add all memory nodes except the selected memory tier > * nodelist to skip list so that we find the best node from the > * memtier nodelist. > @@ -463,7 +463,8 @@ static void establish_demotion_targets(void) > * in the preferred mask when allocating pages during demotion. > */ > do { > - target = find_next_best_node(node, &tier_nodes); > + target = find_next_best_node_in(node, &tier_nodes, > + &node_states[N_MEMORY]); > if (target == NUMA_NO_NODE) > break; > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c4dc61ec663ee..4dde1cbe2fd43 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5779,9 +5779,10 @@ static int numa_zonelist_order_handler(const struct ctl_table *table, int write, > static int node_load[MAX_NUMNODES]; > > /** > - * find_next_best_node - find the next node that should appear in a given node's fallback list > + * find_next_best_node_in - find the next node that should appear in a given node's fallback list > * @node: node whose fallback list we're appending > * @used_node_mask: nodemask_t of already used nodes > + * @candidates: nodemask_t of nodes eligible for selection > * > * We use a number of factors to determine which is the next node that should > * appear on a given node's fallback list. The node should not have appeared > @@ -5793,7 +5794,8 @@ static int node_load[MAX_NUMNODES]; > * > * Return: node id of the found node or %NUMA_NO_NODE if no node is found. > */ > -int find_next_best_node(int node, nodemask_t *used_node_mask) > +int find_next_best_node_in(int node, nodemask_t *used_node_mask, > + const nodemask_t *candidates) > { > int n, val; > int min_val = INT_MAX; > @@ -5803,12 +5805,12 @@ int find_next_best_node(int node, nodemask_t *used_node_mask) > * Use the local node if we haven't already, but for memoryless local > * node, we should skip it and fall back to other nodes. > */ > - if (!node_isset(node, *used_node_mask) && node_state(node, N_MEMORY)) { > + if (!node_isset(node, *used_node_mask) && node_isset(node, *candidates)) { > node_set(node, *used_node_mask); > return node; > } > > - for_each_node_state(n, N_MEMORY) { > + for_each_node_mask(n, *candidates) { > > /* Don't want a node to appear more than once */ > if (node_isset(n, *used_node_mask)) > @@ -5893,7 +5895,8 @@ static void build_zonelists(pg_data_t *pgdat) > prev_node = local_node; > > memset(node_order, 0, sizeof(node_order)); > - while ((node = find_next_best_node(local_node, &used_mask)) >= 0) { > + while ((node = find_next_best_node_in(local_node, &used_mask, > + &node_states[N_MEMORY])) >= 0) { > /* > * We don't want to pressure a particular node. > * So adding penalty to the first node in same