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bh=yM+O9RaRDIJzXpy9G7D7o0f000JhWAb4w/MPXQEEUNY=; b=kA/fJKiethYO6T6us3a5KSmzDSY/071HM3lyrz1jEhcZK1GqUPQvlZPXOtxV/odLJ64bP5 eb/JyGhLmLjvh1dStGJLx/UUndkDwu7diu1l3gnqZmd5G8QMzJzbdrK3lQwrpJmnsNzlTV 9ceeaKnD8VBYAezhInnVPBX9DDsg9aI= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4C29813913; Fri, 13 Jan 2023 13:02:03 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id mvlkEEtWwWNdaAAAMHmgww (envelope-from ); Fri, 13 Jan 2023 13:02:03 +0000 Date: Fri, 13 Jan 2023 14:02:01 +0100 From: Michal Hocko To: Mel Gorman Cc: Andrew Morton , NeilBrown , Thierry Reding , Matthew Wilcox , Vlastimil Babka , Linux-MM , LKML Subject: Re: [PATCH 3/6] mm/page_alloc: Explicitly record high-order atomic allocations in alloc_flags Message-ID: References: <20230113111217.14134-1-mgorman@techsingularity.net> <20230113111217.14134-4-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230113111217.14134-4-mgorman@techsingularity.net> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4E7BC18002C X-Rspam-User: X-Stat-Signature: ngh6nwwjiiaji9uiqb1jzs9pn8bpuo6p X-HE-Tag: 1673614925-319322 X-HE-Meta: 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 HTIXObJ7 1kjcBe2tw/QdzV2s= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri 13-01-23 11:12:14, Mel Gorman wrote: > A high-order ALLOC_HARDER allocation is assumed to be atomic. While that > is accurate, it changes later in the series. In preparation, explicitly > record high-order atomic allocations in gfp_to_alloc_flags(). > > Signed-off-by: Mel Gorman > Acked-by: Vlastimil Babka Acked-by: Michal Hocko > --- > mm/internal.h | 1 + > mm/page_alloc.c | 29 +++++++++++++++++++++++------ > 2 files changed, 24 insertions(+), 6 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 403e4386626d..178484d9fd94 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -746,6 +746,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #else > #define ALLOC_NOFRAGMENT 0x0 > #endif > +#define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ > #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ > > enum ttu_flags; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0040b4e00913..0ef4f3236a5a 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3706,10 +3706,20 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, > * reserved for high-order atomic allocation, so order-0 > * request should skip it. > */ > - if (order > 0 && alloc_flags & ALLOC_HARDER) > + if (alloc_flags & ALLOC_HIGHATOMIC) > page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); > if (!page) { > page = __rmqueue(zone, order, migratetype, alloc_flags); > + > + /* > + * If the allocation fails, allow OOM handling access > + * to HIGHATOMIC reserves as failing now is worse than > + * failing a high-order atomic allocation in the > + * future. > + */ > + if (!page && (alloc_flags & ALLOC_OOM)) > + page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); > + > if (!page) { > spin_unlock_irqrestore(&zone->lock, flags); > return NULL; > @@ -4023,8 +4033,10 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, > return true; > } > #endif > - if (alloc_harder && !free_area_empty(area, MIGRATE_HIGHATOMIC)) > + if ((alloc_flags & (ALLOC_HIGHATOMIC|ALLOC_OOM)) && > + !free_area_empty(area, MIGRATE_HIGHATOMIC)) { > return true; > + } > } > return false; > } > @@ -4286,7 +4298,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > * If this is a high-order atomic allocation then check > * if the pageblock should be reserved for the future > */ > - if (unlikely(order && (alloc_flags & ALLOC_HARDER))) > + if (unlikely(alloc_flags & ALLOC_HIGHATOMIC)) > reserve_highatomic_pageblock(page, zone, order); > > return page; > @@ -4813,7 +4825,7 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask, > } > > static inline unsigned int > -gfp_to_alloc_flags(gfp_t gfp_mask) > +gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) > { > unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; > > @@ -4839,8 +4851,13 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > * Not worth trying to allocate harder for __GFP_NOMEMALLOC even > * if it can't schedule. > */ > - if (!(gfp_mask & __GFP_NOMEMALLOC)) > + if (!(gfp_mask & __GFP_NOMEMALLOC)) { > alloc_flags |= ALLOC_HARDER; > + > + if (order > 0) > + alloc_flags |= ALLOC_HIGHATOMIC; > + } > + > /* > * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the > * comment for __cpuset_node_allowed(). > @@ -5048,7 +5065,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * kswapd needs to be woken up, and to avoid the cost of setting up > * alloc_flags precisely. So we do that now. > */ > - alloc_flags = gfp_to_alloc_flags(gfp_mask); > + alloc_flags = gfp_to_alloc_flags(gfp_mask, order); > > /* > * We need to recalculate the starting point for the zonelist iterator > -- > 2.35.3 -- Michal Hocko SUSE Labs