From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794392574; b=PNPY5Y2asurj8g7fXgxoXG7LE+RBYkEnx+d0GHw8ZnZPPquDoUKvLFat6syIgzcyus28 S8KWNx0GvSfA7NROFegyBnmdxtP9qTquyNfXlUdpHP2Amp1nL4VVyNzMcwhsAtUrP+SUz VPIV+NW+WTqMpp0YSWWogGTHb/Ylm8ticblXUKeYNHpnPcqfnd7Zin00d4edK0mEQV8x+ UhwQ/x/Za9qIks36+dNwG8KqTRsslbbWbbdGu/muRTtvSh2EriPceCHIw6mlAP8Bur1be ybyZ2Nkoh4NGchuSuk0r/iHlCvbQXh0JoGBLMuLJ57D4S42iX+F4Dz1vGp5qNOzV9Dg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794392574; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:Content-Language:To:Cc:References:From:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=xL48yn2OGhXARt11XybDpQ6QVcFFK2xgF3IOcOSuGFY=; b=0duk3yBfZeTtEwTo9OgslP4vS7ulWuye3Y1ulLOwdc7WbkENpQMXJO8S3BNw3feYDHOC 7DBAqO/rMpu9YQ476W8w+mIt6ISsGsW8nJuUvnnHHh+Yut+ThN7h8AnF+H8tZlRNTMlfA yYRllngXJ+4MvRzPWVPY0RkWEhNBr7rRzcuRu/FM2u4efTtb075eyj0ambQSUTCVdHd2N 3jH91XteIZK9hcBMQ8AttsOn0alxHBcHb+uzrHcWlIiHmtnc1g8O0YJEhBTprKC+j4hwg r+9A56psnf0uBoJCycM0JhsIXh4bdwWKLXvVHFLKwUD7wdLJFLieTAwDDeDV3VPmgRQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OHbVXo2O; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26228606A31C for ; Wed, 11 Nov 2026 10:22:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OHbVXo2O Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55E951F00A06; Wed, 11 Nov 2026 10:22:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794392573; bh=xL48yn2OGhXARt11XybDpQ6QVcFFK2xgF3IOcOSuGFY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=OHbVXo2O2RfSkpn2doyIKxnrGsXhG3R45Ni9WY6n1ISklH80KnOANB/JVgcGGcR2B ef0h3EYh5dBbieP6ZDz+MsV5X0bJuaLVyPk68QEuXOgW2raVUwD6PyAYzV+URQNCJF NuRdGbp1PNqskDcCXSAMIa+e9d6ZgOb4sIOG5PLJoFhwpHH92xWxm5KGl6Uoz3Bkr6 T/9rlBYXGWh0vw/OSJwU2Uyrxo16KHBAlbMmbpi5NRKQMCAizVql64LLWve1ro0HYN PViOLAzvpl4LR3td4qobd+/CC2y9xZqNT+/0uii0NQTRtunL0WecccnTC7TRMpfkoX nhTFaYBuzNHSA== Message-ID: <96ab7886-2f8d-4bad-9e22-67c4d1163768@kernel.org> Date: Wed, 11 Nov 2026 11:22:47 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm, vmscan: make kswapd unreserve highatomic pageblocks Content-Language: en-US To: "Jose A. Perez de Azpillaga" , Johannes Weiner Cc: Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Zi Yan , David Hildenbrand , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , JP Kobryn , Frank van der Linden , Thadeu Lima de Souza Cascardo , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20261109-kswapd-highatomic-unreserve-v2-1-6587ca75c77f@kernel.org> <057dc7a4-cdf6-48dd-b326-49c92a936b9b@gmail.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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 BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <057dc7a4-cdf6-48dd-b326-49c92a936b9b@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/10/26 14:25, Jose A. Perez de Azpillaga wrote: > On 11/9/26 11:20 AM, Vlastimil Babka (SUSE) wrote: > [snip] > >> Hook this highatomic unreserve to the moment we exit the loop in >> balance_pgdat() due to exhausting reclaim priority, which means pgdat >> was not balanced and the last kswapd_shrink_node() attempt returned >> false or failed to reclaim anything. Even if that last attempt made the >> pgdat balanced, kswapd was struggling enough, so unreserving is far from >> premature. This should be a more conservative variant of when direct >> reclaim failure triggers the unreserving. Pass force as true to make >> sure repeated failures fully unreserve everything. Also make sure we >> don't count kswapd failures until then. Don't restart immediately as >> the kswapd() loop will call balance_pgdat() again if the unreserve does >> not lead to a balanced pgdat. >> > > the lowest priority gating looks good to me. > > however, sashiko found some concerns [1]. Yeah I saw, and I wonder why there was no email this time. The inability to unreserve when there's no free highatomic pages to grab onto is concerning on its own. Should be a pfn scanner probably. > [1]: > https://sashiko.dev/#/patchset/20261109-kswapd-highatomic-unreserve-v2-1-6587ca75c77f%40kernel.org >