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[2a00:1028:83b8:1e7a:3010:3bd6:8521:caf1]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f20e77asm5427094f8f.0.2026.06.12.04.31.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2026 04:31:58 -0700 (PDT) Date: Fri, 12 Jun 2026 13:31:55 +0200 From: Petr Tesarik To: "Brendan Jackman" Cc: "Andrew Morton" , "David Hildenbrand" , "Lorenzo Stoakes" , "Liam R. Howlett" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , , "Brendan Jackman" , "Johannes Weiner" , "Zi Yan" , Subject: Re: [PATCH v2 1/1] mm: reduce NODE_RECLAIM_xxx and change to enum Message-ID: <20260612133155.71958e80@mordecai> In-Reply-To: References: <20260612085052.59291-1-ptesarik@suse.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-suse-linux-gnu) 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-Transfer-Encoding: 7bit On Fri, 12 Jun 2026 10:10:20 +0000 "Brendan Jackman" wrote: > On Fri Jun 12, 2026 at 8:50 AM UTC, Petr Tesarik wrote: > > Change node_reclaim() to return an enum indicating whether any > > pages have been reclaimed, because that's all the information > > needed by the only caller, get_page_from_freelist(). > > > > This leads to the following translation of the old macro > > identifiers to the new enum values: > > > > - NODE_RECLAIM_NOSCAN -> NODE_RECLAIM_NONE > > - NODE_RECLAIM_FULL -> NODE_RECLAIM_NONE > > - NODE_RECLAIM_SOME -> NODE_RECLAIM_SUCCESS > > - NODE_RECLAIM_SUCCESS -> NODE_RECLAIM_SUCCESS > > > > Originally, I was looking for occurences of NODE_RECLAIM_SOME > > and NODE_RECLAIM_SUCCESS, but I couldn't find any. That's because > > they are typecast from the result of a relational operator. This > > seemed a bit fragile, so I dug a bit deeper and came up with this > > proposed cleanup. > > > > Signed-off-by: Petr Tesarik > > > > -- > > > > Changes from v1: > > - use an enum instead of a bool > > --- > > mm/internal.h | 17 +++++++++-------- > > mm/page_alloc.c | 19 ++++--------------- > > mm/vmscan.c | 18 +++++++++--------- > > 3 files changed, 22 insertions(+), 32 deletions(-) > > > > diff --git a/mm/internal.h b/mm/internal.h > > index 181e79f1d6a20..89b0ea28051c1 100644 > > --- a/mm/internal.h > > +++ b/mm/internal.h > > @@ -1373,23 +1373,24 @@ static inline void mminit_verify_zonelist(void) > > } > > #endif /* CONFIG_DEBUG_MEMORY_INIT */ > > > > -#define NODE_RECLAIM_NOSCAN -2 > > -#define NODE_RECLAIM_FULL -1 > > -#define NODE_RECLAIM_SOME 0 > > -#define NODE_RECLAIM_SUCCESS 1 > > +enum node_reclaim { > > + NODE_RECLAIM_NONE, > > + NODE_RECLAIM_SUCCESS, > > +}; > > > > #ifdef CONFIG_NUMA > > extern int node_reclaim_mode; > > > > -extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int); > > +extern enum node_reclaim 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); > > #else > > #define node_reclaim_mode 0 > > > > -static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask, > > - unsigned int order) > > +static inline enum node_reclaim node_reclaim(struct pglist_data *pgdat, > > + gfp_t mask, unsigned int order) > > { > > - return NODE_RECLAIM_NOSCAN; > > + return NODE_RECLAIM_NONE; > > } > > static inline int find_next_best_node(int node, nodemask_t *used_node_mask) > > { > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index f7db8f049bd23..83a1caac5ac9c 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -3899,8 +3899,6 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > > if (!zone_watermark_fast(zone, order, mark, > > ac->highest_zoneidx, alloc_flags, > > gfp_mask)) { > > - int ret; > > - > > if (cond_accept_memory(zone, order, alloc_flags)) > > goto try_this_zone; > > > > @@ -3921,22 +3919,13 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > > !zone_allows_reclaim(zonelist_zone(ac->preferred_zoneref), zone)) > > continue; > > > > - ret = node_reclaim(zone->zone_pgdat, gfp_mask, order); > > - switch (ret) { > > - case NODE_RECLAIM_NOSCAN: > > - /* did not scan */ > > - continue; > > - case NODE_RECLAIM_FULL: > > - /* scanned but unreclaimable */ > > + if (node_reclaim(zone->zone_pgdat, gfp_mask, order) == NODE_RECLAIM_NONE) > > continue; > > - default: > > - /* did we reclaim enough */ > > - if (zone_watermark_ok(zone, order, mark, > > - ac->highest_zoneidx, alloc_flags)) > > - goto try_this_zone; > > > > + /* did we reclaim enough */ > > + if (!zone_watermark_ok(zone, order, mark, > > + ac->highest_zoneidx, alloc_flags)) > > continue; > > - } > > } > > > > try_this_zone: > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 3f3ff25e561ac..d5bd55620ee9a 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -7786,9 +7786,9 @@ static unsigned long __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, > > return sc->nr_reclaimed; > > } > > > > -int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) > > +enum node_reclaim node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) > > { > > - int ret; > > + unsigned long nr_reclaimed; > > /* Minimum pages needed in order to stay on node */ > > const unsigned long nr_pages = 1 << order; > > struct scan_control sc = { > > @@ -7815,13 +7815,13 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) > > if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && > > node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) <= > > pgdat->min_slab_pages) > > - return NODE_RECLAIM_FULL; > > + return NODE_RECLAIM_NONE; > > > > /* > > * Do not scan if the allocation should not be delayed. > > */ > > if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) > > - return NODE_RECLAIM_NOSCAN; > > + return NODE_RECLAIM_NONE; > > > > /* > > * Only run node reclaim on the local node or on nodes that do not > > @@ -7830,20 +7830,20 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) > > * as wide as possible. > > */ > > if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) > > - return NODE_RECLAIM_NOSCAN; > > + return NODE_RECLAIM_NONE; > > > > if (test_and_set_bit_lock(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) > > - return NODE_RECLAIM_NOSCAN; > > + return NODE_RECLAIM_NONE; > > > > - ret = __node_reclaim(pgdat, gfp_mask, nr_pages, &sc) >= nr_pages; > > + nr_reclaimed = __node_reclaim(pgdat, gfp_mask, nr_pages, &sc); > > clear_bit_unlock(PGDAT_RECLAIM_LOCKED, &pgdat->flags); > > > > - if (ret) > > + if (nr_reclaimed >= nr_pages) > > count_vm_event(PGSCAN_ZONE_RECLAIM_SUCCESS); > > else > > count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); > > > > - return ret; > > + return NODE_RECLAIM_SUCCESS; > > Should that be returning NODE_RECLAIM_NONE when !ret? No. That's the thing. Before my patch, the return value here was either NODE_RECLAIM_SUCCESS (when at least nr_pages were reclaimed), or NODE_RECLAIM_SOME (if less than nr_pages were reclaimed), but the caller makes no distinction, handling both cases in the default label of a switch statement. Petr T