From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BE7B1DE4E6; Wed, 6 Nov 2024 13:22:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730899339; cv=none; b=nOx/m27eJF/46PfqSkiMhbbYuRE1cS1OiSm8Yy3DFZO8OdppX6kx82jt/h4X8wIzEtI7AsR4OkhMeRzTLE0Acz6R9tuIBo/atzRALkrS49kHORfmefynd2Byk18H03bka/Udgnyy1s/VSuWZs9nUqfHrMreQrSqRCqdPnjlOHEg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730899339; c=relaxed/simple; bh=xpB99pPfHyzswOIeoeSOQhIxl4Vco047Xjnnp+qfBWU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CuBoDV6NKFbWB6xLzje3DgwP99eKFUJSGNVAS/nvOZ3L8PSYlM+W4QHmxZDUY1PXPleA/hJgT1aMVLlU2mEUZXuTrJ6hN7xoymxttrD7llqmLjTIyEpYCQWGwWTgC7KIJDEdIHmNhjQfpPgZDEm/jQDgsX/5gdoswfCNDKr0Pag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EZgXdcC0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EZgXdcC0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 960CBC4CECD; Wed, 6 Nov 2024 13:22:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730899339; bh=xpB99pPfHyzswOIeoeSOQhIxl4Vco047Xjnnp+qfBWU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EZgXdcC0uOpOAc38PQ3niVd/XoIi6vVxA4lNZsDDBESm8epHdhQDetsTi96hBs3Sq h5wDSBB6QVKhb2zABKlJQ52Et0YsozkXQv5Tfvt62oVBuKGHH/qPJHUO8aBIDg3C2M 6rXK6eTF778GSaUjWGoUSCT3lwYlhdlPocaBq8zQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mel Gorman , Vlastimil Babka , Michal Hocko , Matthew Wilcox , NeilBrown , Thierry Reding , Andrew Morton , Sasha Levin Subject: [PATCH 5.15 62/73] mm/page_alloc: explicitly define what alloc flags deplete min reserves Date: Wed, 6 Nov 2024 13:06:06 +0100 Message-ID: <20241106120301.802616957@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120259.955073160@linuxfoundation.org> References: <20241106120259.955073160@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mel Gorman [ Upstream commit ab3508854353793cd35e348fde89a5c09b2fd8b5 ] As there are more ALLOC_ flags that affect reserves, define what flags affect reserves and clarify the effect of each flag. Link: https://lkml.kernel.org/r/20230113111217.14134-5-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Matthew Wilcox Cc: NeilBrown Cc: Thierry Reding Signed-off-by: Andrew Morton Stable-dep-of: 281dd25c1a01 ("mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves") Signed-off-by: Sasha Levin --- 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 136f435e0f1ab..717e75313693c 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -606,6 +606,9 @@ 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 43122de999c4c..7778c2b11d8cb 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3838,15 +3838,14 @@ 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 @@ -3870,25 +3869,36 @@ 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; } /* -- 2.43.0