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Thu, 8 Dec 2022 16:51:12 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id k7E/CQAWkmPgMQAAMHmgww (envelope-from ); Thu, 08 Dec 2022 16:51:12 +0000 Message-ID: <915a5034-53e6-9464-3fc7-4d1b5a0aa26d@suse.cz> Date: Thu, 8 Dec 2022 17:51:11 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH 3/6] mm/page_alloc: Explicitly record high-order atomic allocations in alloc_flags Content-Language: en-US To: Mel Gorman , Linux-MM Cc: Andrew Morton , Michal Hocko , NeilBrown , Thierry Reding , Matthew Wilcox , LKML References: <20221129151701.23261-1-mgorman@techsingularity.net> <20221129151701.23261-4-mgorman@techsingularity.net> From: Vlastimil Babka In-Reply-To: <20221129151701.23261-4-mgorman@techsingularity.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BF25C100012 X-Stat-Signature: bjy8crc1qnr4ugb486f3qphh8city4qc X-HE-Tag: 1670518273-400515 X-HE-Meta: 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 GIOlWY0i Z5X9WJv8oEPrB5oo4eGY+TRRj1AJux/BWEL4u1WoN4cuoA9w7xdQo2ycNBQ== 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 11/29/22 16:16, 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 > --- > mm/internal.h | 1 + > mm/page_alloc.c | 19 +++++++++++++------ > 2 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index d503e57a57a1..9a9d9b5ee87f 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -754,6 +754,7 @@ 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 da746e9eb2cf..e2b65767dda0 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3710,7 +3710,7 @@ 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); > @@ -4028,8 +4028,10 @@ 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) && > + !free_area_empty(area, MIGRATE_HIGHATOMIC)) { > return true; alloc_harder is defined as (alloc_flags & (ALLOC_HARDER|ALLOC_OOM)); AFAICS this means we no longer allow ALLOC_OOM to use the highatomic reserve. Isn't that a risk? > + } > } > return false; > } > @@ -4291,7 +4293,7 @@ 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; > @@ -4818,7 +4820,7 @@ 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; > > @@ -4844,8 +4846,13 @@ 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(). > @@ -5053,7 +5060,7 @@ __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