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9 Jan 2023 15:17:25 -0000 From: Mel Gorman To: Linux-MM Cc: Andrew Morton , Michal Hocko , NeilBrown , Thierry Reding , Matthew Wilcox , Vlastimil Babka , LKML , Mel Gorman Subject: [PATCH 4/7] mm/page_alloc: Explicitly define what alloc flags deplete min reserves Date: Mon, 9 Jan 2023 15:16:28 +0000 Message-Id: <20230109151631.24923-5-mgorman@techsingularity.net> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230109151631.24923-1-mgorman@techsingularity.net> References: <20230109151631.24923-1-mgorman@techsingularity.net> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C005D8001C X-Stat-Signature: shzc1aobj9dzpcdyzdx1dt77xjgnm5dm X-HE-Tag: 1673277446-50328 X-HE-Meta: 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 em2K5UgO myEqr0LCEPkZJKn6yGi+OPTn2KQ48goad+QR4VlogZZ5VYTTrjm/mNuKHFUVVshaXHe06 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: As there are more ALLOC_ flags that affect reserves, define what flags affect reserves and clarify the effect of each flag. Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Acked-by: Michal Hocko --- mm/internal.h | 3 +++ mm/page_alloc.c | 34 ++++++++++++++++++++++------------ 2 files changed, 25 insertions(+), 12 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 178484d9fd94..8706d46863df 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -749,6 +749,9 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ +/* Flags that allow allocations below the min watermark. */ +#define ALLOC_RESERVES (ALLOC_HARDER|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) + enum ttu_flags; struct tlbflush_unmap_batch; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0ef4f3236a5a..6f41b84a97ac 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3949,15 +3949,14 @@ ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE); static inline long __zone_watermark_unusable_free(struct zone *z, unsigned int order, unsigned int alloc_flags) { - const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM)); long unusable_free = (1 << order) - 1; /* - * If the caller does not have rights to ALLOC_HARDER then subtract - * the high-atomic reserves. This will over-estimate the size of the - * atomic reserve but it avoids a search. + * If the caller does not have rights to reserves below the min + * watermark then subtract the high-atomic reserves. This will + * over-estimate the size of the atomic reserve but it avoids a search. */ - if (likely(!alloc_harder)) + if (likely(!(alloc_flags & ALLOC_RESERVES))) unusable_free += z->nr_reserved_highatomic; #ifdef CONFIG_CMA @@ -3981,25 +3980,36 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, { long min = mark; int o; - const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM)); /* free_pages may go negative - that's OK */ free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags); - if (alloc_flags & ALLOC_MIN_RESERVE) - min -= min / 2; + if (unlikely(alloc_flags & ALLOC_RESERVES)) { + /* + * __GFP_HIGH allows access to 50% of the min reserve as well + * as OOM. + */ + if (alloc_flags & ALLOC_MIN_RESERVE) + min -= min / 2; - if (unlikely(alloc_harder)) { /* - * OOM victims can try even harder than normal ALLOC_HARDER + * Non-blocking allocations can access some of the reserve + * with more access if also __GFP_HIGH. The reasoning is that + * a non-blocking caller may incur a more severe penalty + * if it cannot get memory quickly, particularly if it's + * also __GFP_HIGH. + */ + if (alloc_flags & ALLOC_HARDER) + min -= min / 4; + + /* + * OOM victims can try even harder than the normal reserve * users on the grounds that it's definitely going to be in * the exit path shortly and free memory. Any allocation it * makes during the free path will be small and short-lived. */ if (alloc_flags & ALLOC_OOM) min -= min / 2; - else - min -= min / 4; } /*