From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 365D2EF48E8 for ; Fri, 13 Feb 2026 08:46:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4922E6B0005; Fri, 13 Feb 2026 03:46:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 440156B0089; Fri, 13 Feb 2026 03:46:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2F7996B008A; Fri, 13 Feb 2026 03:46:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 1C7A76B0005 for ; Fri, 13 Feb 2026 03:46:20 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 2393013AD41 for ; Fri, 13 Feb 2026 08:46:19 +0000 (UTC) X-FDA: 84438801678.26.47C7DA5 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf08.hostedemail.com (Postfix) with ESMTP id A35BE160006 for ; Fri, 13 Feb 2026 08:46:16 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IfuFinF9; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=7bFjfbm7; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=HaAgs4JF; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=iCuEZKSA; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770972377; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=M6CtYIdpGRPdr5YJBB51g/H26wkAcNK4Ssdrvyg0HpU=; b=xCZt76p8wPPIAdys2dYXHEmFvrKi1AePXJIwKFJM95CJnBmYBPl1/5n2DJ46IQ5L7azFVn 4U2NK5GU7Pj0rShAvwKXj5pdwuuF7SVqcbUYZhGKYvRb2wV/Q4SJOdxMhHOD0uhGxwpxw1 Knu83iQp7S2RClK7LJjDS1vQ8lD+73M= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IfuFinF9; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=7bFjfbm7; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=HaAgs4JF; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=iCuEZKSA; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770972377; a=rsa-sha256; cv=none; b=Kau99ADiqzqHEunQem5/QRudIlsmfIGpg9+5EgHyBNYDdI0CBwpjQN4pJqu6EkLjoZ2n+R OxjQxnCraCESCQ0kTorrKSR2FWjfZUwyyIl3XAegCJ4kxet1aI5/OWvrtnOMK/OYpzYUd8 MOjJZ5E1WZ4fDGcOxqISn3YzZqH3aMw= Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id B8CB65BCC4; Fri, 13 Feb 2026 08:46:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1770972375; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=M6CtYIdpGRPdr5YJBB51g/H26wkAcNK4Ssdrvyg0HpU=; b=IfuFinF9bZM04PjikfvkhahiDsVKI4RCmXM9xqk8pcd2UaCuvrDeLVXhnWMBeb2J8gNS1x EMG9jVzhIkaHtMoabtyoMu1X4K23rwVI0amDLjNNhsX6hQGFPYByLiZlWWnXm0YhG2RciN 9uv/6GazI+QhV1iqNNi/k7WmdmckZDk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1770972375; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=M6CtYIdpGRPdr5YJBB51g/H26wkAcNK4Ssdrvyg0HpU=; b=7bFjfbm7azFrch5t22beas6meSFYyvoJq3cmXtxZtpdLFCpuvaNNe8AaAYVMwmzFpVQguq xdvnZN9Sv02oK+Ag== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1770972374; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=M6CtYIdpGRPdr5YJBB51g/H26wkAcNK4Ssdrvyg0HpU=; b=HaAgs4JFQk/w+uSkmmKxOgZaFG13shzu/gE7pRO0txjbZ9a5rPn1BNf3vTRHvDl9XGcUI3 /l4NcL44dUX5/xtcEuTh3I96ofyPmz0mpjzhG9y4dKPLY6adSfjQIXNkFks/qN5sWxcQHx 50jpvYIvhKmqxSUh+z29nioVmPBzboY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1770972374; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=M6CtYIdpGRPdr5YJBB51g/H26wkAcNK4Ssdrvyg0HpU=; b=iCuEZKSABPYTXxrtHBx+i6jJY9t2wDqw8s6NR1g2H32fk0M8liXbY1t4WUEQ4UfRPR2M51 rUQ9+1po6jFeZ7Dg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 8E54C3EA62; Fri, 13 Feb 2026 08:46:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id BCMhItbkjml6MQAAD6G6ig (envelope-from ); Fri, 13 Feb 2026 08:46:14 +0000 Message-ID: Date: Fri, 13 Feb 2026 09:46:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9] mm/page_alloc: boost watermarks on atomic allocation failure Content-Language: en-US To: Qiliang Yuan , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Wei Xu , Brendan Jackman , Johannes Weiner , Zi Yan , Lance Yang , SeongJae Park Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260213-wujing-mm-page_alloc-v8-v9-1-cd99f3a6cb70@gmail.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <20260213-wujing-mm-page_alloc-v8-v9-1-cd99f3a6cb70@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A35BE160006 X-Stat-Signature: gm43pkbzk3owhwqjmje8zx3jom41jkub X-Rspam-User: X-HE-Tag: 1770972376-404222 X-HE-Meta: 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 kyRw5yj1 UytmG9S5y8wtYD3XlHnmdbwTmB5nNhkmmtlYzv/+ANio3lAlx8Knv/hJ5WgEl/jx4GeDfLGDXFkTblgp4ItZ9XsGfO3NM32t3zoIPTotvJ37rG7Zp7Kn/moTu489Gr1JUT0dzeNxRMujDWzQksz1Aqda0ucmbVo3FQhIAHPqS+sjmfey2vZO6MCHgv1jNK3O7L+BfFk/rFcKDsuw6J9DeScdaSaTQPt6MEE/j2l90y4kr4tNO9pbyxFv9sJb/S0SmQ8WRKukxOoviVohQnVqSBjHD+54afVeJhRZS5wu1gALs/Jea3fMwrUnwRP9/xATtpzoUEhzogK+A4D6J2BkzyRCAwQbg0jyf14kxvfUmCss0d2Ij2w+WoCsd+gz3u+uE4a7T 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: List-Subscribe: List-Unsubscribe: On 2/13/26 04:17, Qiliang Yuan wrote: > Atomic allocations (GFP_ATOMIC) are prone to failure under heavy memory > pressure as they cannot enter direct reclaim. This patch introduces a > watermark boost mechanism to mitigate this issue. > > When a GFP_ATOMIC request enters the slowpath, the preferred zone's > watermark_boost is increased under zone->lock protection. This triggers > kswapd to proactively reclaim memory, creating a safety buffer for > future atomic allocations. A 1-second debounce timer prevents excessive > boosts during traffic bursts. > > This approach reuses existing watermark_boost infrastructure with > minimal overhead and proper locking to ensure thread safety. > > Allocation failure logs: > [38535644.718700] node 0: slabs: 1031, objs: 43328, free: 0 > [38535644.725059] node 1: slabs: 339, objs: 17616, free: 317 > [38535645.428345] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC) > [38535645.436888] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0 > [38535645.447664] node 0: slabs: 940, objs: 40864, free: 144 > [38535645.454026] node 1: slabs: 322, objs: 19168, free: 383 > [38535645.556122] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC) > [38535645.564576] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0 > [38535649.655523] warn_alloc: 59 callbacks suppressed > [38535649.655527] swapper/100: page allocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=(null) > [38535649.671692] swapper/100 cpuset=/ mems_allowed=0-1 > > Acked-by: Vlastimil Babka > Signed-off-by: Qiliang Yuan > --- > v9: > - Use mult_frac() for boost calculation. (SJ) > - Add !can_direct_reclaim check. (Vlastimil) > - Code cleanup: naming, scope, and line limits. (SJ) > - Update tags: Add Vlastimil's Acked-by. > > v8: > - Use spin_lock_irqsave() to prevent inconsistent lock state. > > v7: > - Use local variable for boost_amount. > - Add zone->lock protection. > - Add lockdep assertion. > > v6: > - Use ATOMIC_BOOST_SCALE_SHIFT define. > - Add documentation for 0.1% rationale. > > v5: > - Use native boost_watermark(). > > v4: > - Add watermark_scale_boost and gradual decay. > > v3: > - Per-zone debounce timer. > > v2: > - Debounce logic and zone-proportional boosting. > > v1: > - Initial version. > --- > Link to v8: https://lore.kernel.org/r/20260212-wujing-mm-page_alloc-v8-v8-1-daba38990cd3@gmail.com > --- > include/linux/mmzone.h | 1 + > mm/page_alloc.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 48 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 75ef7c9f9307..8e37e4e6765b 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -882,6 +882,7 @@ struct zone { > /* zone watermarks, access with *_wmark_pages(zone) macros */ > unsigned long _watermark[NR_WMARK]; > unsigned long watermark_boost; > + unsigned long last_boost_jiffies; > > unsigned long nr_reserved_highatomic; > unsigned long nr_free_highatomic; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c380f063e8b7..8af88584a8bd 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -218,6 +218,13 @@ unsigned int pageblock_order __read_mostly; > static void __free_pages_ok(struct page *page, unsigned int order, > fpi_t fpi_flags); > > +/* > + * Boost watermarks by ~0.1% of zone size on atomic allocation pressure. > + * This provides zone-proportional safety buffers: ~1MB per 1GB of zone size. > + * Larger zones under GFP_ATOMIC pressure need proportionally larger reserves. > + */ > +#define ATOMIC_BOOST_FACTOR 1 ... so now we #define 1 but it makes little sense without that hardcoded 1000 below. > + > /* > * results with 256, 32 in the lowmem_reserve sysctl: > * 1G machine -> (16M dma, 800M-16M normal, 1G-800M high) > @@ -2161,6 +2168,9 @@ bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *pag > static inline bool boost_watermark(struct zone *zone) > { > unsigned long max_boost; > + unsigned long boost_amount; > + > + lockdep_assert_held(&zone->lock); > > if (!watermark_boost_factor) > return false; > @@ -2189,12 +2199,43 @@ static inline bool boost_watermark(struct zone *zone) > > max_boost = max(pageblock_nr_pages, max_boost); > > - zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages, > - max_boost); > + boost_amount = max(pageblock_nr_pages, > + mult_frac(zone_managed_pages(zone), ATOMIC_BOOST_FACTOR, 1000)); I don't think mult_frac() was a great suggestion. We're talking about right shifting by a constant 10. In the other cases of mult_frac() we use dynamic values for x and n so it's justified. But this IMHO is unnecessary complication. > + zone->watermark_boost = min(zone->watermark_boost + boost_amount, > + max_boost); > > return true; > } > > +static void boost_zone_for_atomic(struct alloc_context *ac, gfp_t gfp_mask) > +{ > + struct zoneref *z; > + struct zone *zone; > + unsigned long now = jiffies; > + > + for_each_zone_zonelist(zone, z, ac->zonelist, ac->highest_zoneidx) { > + /* Rate-limit boosts to once per second per zone */ > + if (time_after(now, zone->last_boost_jiffies + HZ)) { > + unsigned long flags; > + bool should_wake; > + > + zone->last_boost_jiffies = now; > + > + /* Modify watermark under lock, wake kswapd outside */ > + spin_lock_irqsave(&zone->lock, flags); > + should_wake = boost_watermark(zone); > + spin_unlock_irqrestore(&zone->lock, flags); > + > + if (should_wake) > + wakeup_kswapd(zone, gfp_mask, 0, > + ac->highest_zoneidx); > + > + /* Boost only the preferred zone */ > + break; > + } > + } > +} > + > /* > * When we are falling back to another migratetype during allocation, should we > * try to claim an entire block to satisfy further allocations, instead of > @@ -4742,6 +4783,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > if (page) > goto got_pg; > > + /* Boost watermarks for atomic requests entering slowpath */ > + if ((gfp_mask & GFP_ATOMIC) && order == 0 && !can_direct_reclaim) > + boost_zone_for_atomic(ac, gfp_mask); > + > /* > * For costly allocations, try direct compaction first, as it's likely > * that we have enough base pages and don't need to reclaim. For non- > > --- > base-commit: b54345928fa1dbde534e32ecaa138678fd5d2135 > change-id: 20260206-wujing-mm-page_alloc-v8-fb1979bac6fe > > Best regards,