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 DDF4AC982E6 for ; Mon, 21 Sep 2026 15:58:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BC3596B0096; Mon, 21 Sep 2026 11:58:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B74336B00C1; Mon, 21 Sep 2026 11:58:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A632B6B00C5; Mon, 21 Sep 2026 11:58:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 7BD5B6B0096 for ; Mon, 21 Sep 2026 11:58:57 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 0C47D1C1933 for ; Mon, 21 Sep 2026 15:58:57 +0000 (UTC) X-FDA: 85238227914.30.C720EBA Received: from mail-qv2-f27.google.com (mail-qv2-f27.google.com [74.125.230.155]) by imf25.hostedemail.com (Postfix) with ESMTP id E3B4CA0005 for ; Mon, 21 Sep 2026 15:58:54 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=cmpxchg.org header.s=google header.b=NaXP2gZz; dmarc=pass (policy=none) header.from=cmpxchg.org; spf=pass (imf25.hostedemail.com: domain of hannes@cmpxchg.org designates 74.125.230.155 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790006335; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=YMayVPzqy74wYsK2+s0iOp7Kd4xLwxOjegiyzaJMk4o=; b=HML+ybocScOawG1ZjpkVwK/2+TwdgxynRUTyABrB1kzgqbVSHFrhpIdx0hN8fSsJGuMo9C OfNVVzYO7ejjn+4F0+AKxp/U4npcVQz1Sf5UE0F32QYz1aotUGM1TmYYe7MoD2tly5WYY4 SKgBsWWTiPrCspcgu9fda3fecQ56I3Q= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790006335; b=jC9r5XQgy3wqRI/wa5ic6clfZ/iza+BYJpjXyhj92h7myIIqNB7mbzGjMlB0RPDmSBnt+e i5CjcgwHtYU6s08saYYx//f7ZPhWbz0JtSSvakd0RzDF8jEoPOIIMYjT5z17xDai3iUyLY eFLp+wJQICYP6lkkBNBdSEddcrrUdK8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=cmpxchg.org header.s=google header.b=NaXP2gZz; dmarc=pass (policy=none) header.from=cmpxchg.org; spf=pass (imf25.hostedemail.com: domain of hannes@cmpxchg.org designates 74.125.230.155 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org Received: by mail-qv2-f27.google.com with SMTP id 6a1803df08f44-9104649a5dcso28690056d6.3 for ; Mon, 21 Sep 2026 08:58:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg.org; s=google; t=1790006334; x=1790611134; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=YMayVPzqy74wYsK2+s0iOp7Kd4xLwxOjegiyzaJMk4o=; b=NaXP2gZz1w3WNa1yPoAEcY6wLWbzuXpiDh5yGR3ailOiV0uXK929lD/AoA/K6+NV5Z s1eerOng4Dodunkd+2t3ya4DVuEa6KnqxpIQ8g8OVHvtPzRrHVMWT91Ceu0wMiSgIJjP s45aS2mYmqAVaYyH0/t1dCl4ovf0/8KRFzG/7NV3HiOhrELf9KznhxDAuYSovSLPfqoo SaBDDxZncPRPGPwEFoYyo6fn4JnHkJOhifOZfyDZiyEcI9pVEy/rU4rxvTE+DyazX3jR wI6bPaQ3K71hTrvKI53i0Xwgr784emh/ZSRFUoGv49kGiMDVzSDJG4N5XuCvE0TkPwjs twFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790006334; x=1790611134; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=YMayVPzqy74wYsK2+s0iOp7Kd4xLwxOjegiyzaJMk4o=; b=Ht1FsZXTRERg9DYmtPqOgAdoyzd4NZzKe+JJ6m+od68uNJfWMX/8JLxkrL7cG5gP3h HhSWW3Jt2l6oE4j/TwOVvrKYZ+XRFPRUFDE4GXt9kJIX4e+VNXxQN6rU4BemGT8f5f1z vfRqbE7/c5OeDn/oUlQ7z4Z0R4MRfmODAiV/LPrElf8bYVHxBUbFYdbHRKECnmCFMfR2 KC4xboHMw3vJ02NksFIWeTAlf7knbtlXq1M6dAnnOUiGobt40uOgJBG3YzlipOmnevvn f+GjOG0Dr61222hgDzIbJ6zIqWYmDrK6iXR9kFjsI7jcdmQPMryaydxvBnjOkQTkpIyd /kjg== X-Forwarded-Encrypted: i=1; AKwUvBwitBCgw4ha2v1TL7JGVljRJQIQhrRw4XG9JkH2H4G/Rd0qfI6HWzCht/TgEgLdwbBlQy47B/gAmg==@kvack.org X-Gm-Message-State: AFuF++ktvNO0SQky7J2LMyZ/K72KOnfoGRlRbTSZfYDfvZlGJrVD1rOr YvZQf/2RiFfp0nJXOy4lTCRLdk28dTVeRd5FW09zE7KZyc7/IUy+o7utu1tGJTZ8scI= X-Gm-Gg: AYBFou1f8w72Po6QcyABoCsW84jdN1xzuFHxAjjNw+gmwJzs9EfOwYnp3ajGgw10wUw dy1V6FtdmT5hpdLueZostBFW7cuCy4/s+d07OGaEJc7gw9cdLGsROIL5Kb23wiX1im0kNeTUj2l XXtSTOuIEovtJl23hyiuhPEzDmps4h/8ugHTyycXV2gmBZkLbdsqTZJqMM0gdwAq4KCD3YzFc2t y5eQAX58G93Hrw0/VzKj1BsE1cuRG8F2/WEFmU8scQERZ34jFgWjPa6B3d/0eAWWEdZHGY4zHgg b3eZvpkZvCpOqO824K5at33kEsp0SgDi9G09DW3FSPL2/Vug4a3UhYy7tP2WrJwwG53N/oEBJ7+ SohqzixJ/L397byEoDC9TbgoZqdZScFSSMOqyB+g8p3oVoSKmY1IQ++3XBRazpUPIw7yEk1/EI9 1G/7OlEAsGgjjgTBSLyyrpqpHGjF3ZYy/CIfVYQxE2bmFwgeUC4suyzS+luVmigSLy5U7ya9gsm s73rkY= X-Received: by 2002:a05:6214:27ee:b0:912:6067:f517 with SMTP id 6a1803df08f44-913fc979c79mr11430666d6.46.1790006333775; Mon, 21 Sep 2026 08:58:53 -0700 (PDT) Received: from localhost ([2603:7001:f100:500:365a:60ff:fe62:ff29]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-91260a86f62sm70283746d6.33.2026.09.21.08.58.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2026 08:58:53 -0700 (PDT) Date: Mon, 21 Sep 2026 11:58:52 -0400 From: Johannes Weiner To: Matthew Wilcox Cc: "Vlastimil Babka (SUSE)" , Matt Fleming , Salvatore Dipietro , akpm@linux-foundation.org, abuehaze@amazon.com, alisaidi@amazon.com, blakgeof@amazon.com, brauner@kernel.org, brendan.jackman@linux.dev, david@redhat.com, dgc@kernel.org, dipietro.salvatore@gmail.com, djwong@kernel.org, hch@infradead.org, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, mhocko@suse.com, ritesh.list@gmail.com, rvvandan@amazon.com, stable@vger.kernel.org, surenb@google.com, ziy@nvidia.com Subject: Re: [PATCH 1/2] mm: page_alloc: do not give all non-blocking requests reserve access Message-ID: References: <20260905174239.99e31515fabe220aa7d8e6fa@linux-foundation.org> <20260910114602.926944-1-dipiets@amazon.it> <8d6a8a63-4adc-458a-b548-a47bf5ff8eb7@kernel.org> <9f415dc7-adad-4161-b20d-7c3173f50ff3@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E3B4CA0005 X-Stat-Signature: j7z4961jt5dsatw3ifiq1n7fxh9p5o8j X-HE-Tag: 1790006334-947374 X-HE-Meta: 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 hprVNUMV 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 21, 2026 at 03:54:32PM +0100, Matthew Wilcox wrote: > On Mon, Sep 21, 2026 at 10:38:18AM -0400, Johannes Weiner wrote: > > +++ b/mm/page_alloc.c > > @@ -3246,7 +3246,9 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, > > * reserves as failing now is worse than failing a > > * high-order atomic allocation in the future. > > */ > > - if (!page && (alloc_flags & (ALLOC_OOM|ALLOC_NON_BLOCK))) > > + if (!page && > > + ((alloc_flags & ALLOC_OOM) || > > + (alloc_flags & ALLOC_MASK_ATOMIC) == ALLOC_MASK_ATOMIC)) > > page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); > > Would this be slightly neater? > > static inline bool may_access_reserves(unsigned int alloc_flags) > { > if (alloc_flags & ALLOC_OOM) > return true; > if (alloc_flags & (ALLOC_NON_BLOCK | ALLOC_MIN_RESERVE)) == > (ALLOC_NON_BLOCK | ALLOC_MIN_RESERVE) > return true; > return false; > } I tend to be hesitant with single-use abstractions, but no objection if people think this is better.