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 5A443C982CC for ; Thu, 17 Sep 2026 03:13:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6FAE96B0092; Wed, 16 Sep 2026 23:13:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6ACBF6B0093; Wed, 16 Sep 2026 23:13:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5753C6B0095; Wed, 16 Sep 2026 23:13:13 -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 395FA6B0092 for ; Wed, 16 Sep 2026 23:13:13 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 2FBA51601FC for ; Thu, 17 Sep 2026 03:13:12 +0000 (UTC) X-FDA: 85221783024.27.2C9537D Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf09.hostedemail.com (Postfix) with ESMTP id 727FB140005 for ; Thu, 17 Sep 2026 03:13:10 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=hBiJNpgS; spf=pass (imf09.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1789614790; 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=4+BlsAYVIvUfCkO04DyxIYq5YEbiYoDvPQdBOWVcg8o=; b=bcdP2rGX9gGOIJzbtXOrV3IIVSqlpCJSr9r6FwYhKQoJBOO4Q2BzREm3jI8cf+6Hxf7G8x BNkyZhmm66wEQTwrff7dprLANlu8ltGBFCFaaiTVbHVX6ysYkEkI1h+aQFzKDWdX7HRldt iS17/KVRjVkvWOFY0IeJexxKBRLvfAQ= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=hBiJNpgS; spf=pass (imf09.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1789614790; b=BHJIPrTtc7ko180oMYpQjfU5sbh6kuDY47THY/msSbFeI6bhfNF0rbt0v1UHqGgbmJ8iPR MopaKoy7Nn7cLGc2sfoiillVvYABlyir6C8W26B0BYl1l3faDwbB3sDvaXbIjSJz6GfIxh aqlJpzMgWnn1tmK8/cimdEgHKPRMrIE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id BD4FF601EF; Thu, 17 Sep 2026 03:13:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 585591F000FF; Thu, 17 Sep 2026 03:13:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789614789; bh=4+BlsAYVIvUfCkO04DyxIYq5YEbiYoDvPQdBOWVcg8o=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=hBiJNpgSIbLu448u25HbOQo5bMiPEncJqYfjeZJAyyhF3R2RWKukQ0My/1W9qgG3R q3ZcrXWQhRwuXALKX0cvM2ivn55BXK0d66EDShx8vS4aXs2nPxIzsrdzkPWUeXzqDh N54rEOf2/SDOY4l38oMMQhB+BQjSTR5m7Mz1loYY= Date: Wed, 16 Sep 2026 20:13:07 -0700 From: Andrew Morton To: ackerleytng@google.com Cc: Ackerley Tng via B4 Relay , Alex Shi , David Hildenbrand , Dongliang Mu , Hongxiang Lou , Johannes Weiner , Jonathan Corbet , Joshua Hahn , "Liam R. Howlett" , Lorenzo Stoakes , Miaohe Lin , Michal Hocko , Mike Rapoport , Muchun Song , Nhat Pham , Oscar Salvador , Peter Xu , Randy Dunlap , Roman Gushchin , Shakeel Butt , Shuah Khan , Suren Baghdasaryan , Usama Arif , Vlastimil Babka , Wupeng Ma , Yanteng Si , Naoya Horiguchi , fvdl@google.com, jthoughton@google.com, rientjes@google.com, vannapurve@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: Re: [PATCH v3 0/4] Fix HugeTLB subpool used_hpages tracking Message-Id: <20260916201307.5618114cbac4af52d98aecfa@linux-foundation.org> In-Reply-To: <20260916-hugetlb-subpool-always-track-used-v3-0-38aae9b5ccdd@google.com> References: <20260916-hugetlb-subpool-always-track-used-v3-0-38aae9b5ccdd@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 727FB140005 X-Stat-Signature: w7qcejz74s319c5s7jgnndebhimy3uau X-Rspam-User: X-HE-Tag: 1789614790-660421 X-HE-Meta: U2FsdGVkX19iLOLBslN1eP+U9jqYJbsriULULxmG7e7io6ywdqwwvWXGQdt6fXUEjUflcH4L9h9+ZuFgmCd0+Ce4O4iCY8SPw6DQ+D9qoVbAvduoD8wI2XoIoHMy1JRDQYLMjGx2xN9GhW8HnwaMCZRUlRe3NKwcQWeJN8Qn2Ukj/R6gs1qjePppaAavNZWSjXdl1ybe9Y+PlstT+NF6Er61oSPaOZ+atZnWUiI0oB8clhXc5eL1XqAlKsGZsJoPJw5rWLAxz6J8gMg5EeDU2c5B391WFvZIxg3p7Scqgled6trr2d5V9KBzzTJOSwxFVpKoDXzIUg9bZwjzWkH7a6jyGskpVkAFuKPhNLG17cNTI6nbZr/69PBczk/6VRJ6Yk0rDHcqFjbZJv6oKCcCKpSySpi/FrtNSNlMgHLrsTSGJHCn1EbBGHCHgu5oSYeD5uHSxsJYZkp+MrKm9IzCTH4JpsssLHmMdNdaLHgZf2zU/PJajVDn6++ZrbBo6u0cKUGlE9VKRarpF7osMGyyDC4pqYlaG2k9q23+jfLpHQtjgJNtTLvjTza4sXeanMQD3TdwmIevYR4XyIveUTNgAEeClCHRAEAQhuq4kxAw9qVUxunwL1uRFr3bPa0TM6ChAnHlP0hoHuK7Z9ykcJmQB4aqfy1NtX+IkkUo28ynlhK2T0HxhfD8SVLvPRskGxAtosdA4kpD4QKs0mXkpXiPowibhiTCOobpDxHUmda7QDUCpkhO6or743cjJ1K76Y/yaUd4A/h/5okOVxO69dyktZDcI+CtM7O08lZC7JW4yUzenn872cRfLq+DGeeQxjS7lE4Z994JA0qqr/Ap12y9oKfHiRzGprvqoNlNy5bGuQW/oPSxeiqLD1lIZ2+eRE/bxb2h2NEJ6Ry8GKTAwJnAsUx0AA38w7hOB5B4kg1dP3Pu6TVseesl4z9oYd+BNQjVyBQRDZt+rRrVZhPQjdI mgwEt9gk 2PsNLjnhxKVcGjwRkAdtQ/AFqTEFvRp3N6HjNhkY3JMpTaowlqSiv6lR/H4/ib4a6VPpIY7ORjum2zvAgJ45NEXZFINAd75ZlXyPIbhjm2S1LVQ8iDg/jcExGq8OH8zZvCG9mIvi5dX2InPQJo2yqaVcA36Vyt6MqjVww30a6yJ6of1zz7/cIozxMBv4yuXeTf2TQ5jbrxoCnRi40c+u6S6NDCwKgQPE/wWDsNZuWzviFGJcuAlkPA+v4db6qepKaLloTwfsyp6UsY0KqcP05GU7WMQmQfmgRSGWOnLuvwVnRhyQWTWVcJDs4ega5Y7nZV2rN8Ey1mZjOjXjrcNknRUbCur+i9UEk2CfiGlAPD+KwkMK4wEnMFTNgJsaXDWGHvmy/ACB/xkvODqmVhVXTk6Ks27KGaSPX4sWGpvrB7VUnUJUo3FYUwVLdpve5kgMy7nhjIO+55vNvFd4lquWvymYNAwjrXTjK8nzOLTpKPYFDTcdAupGKZFqxFNiANZAwcvJELlL6GoZfDoKGR9byIL8q5heKPokF28w0 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 16 Sep 2026 16:39:00 -0700 Ackerley Tng via B4 Relay wrote: > HugeTLB subpools currently only track used pages (used_hpages) when a > maximum size limit (max_hpages) is configured on the mount. > > ... > > This series addresses three problem areas resulting from untracked usage > and asymmetric error handling: These are rather serious-sounding problems. I'm seeing Fixes: for 10-year-old patches, for one last year and one this year. The fourth patch doesn't identify what to fix. So if downstream people (-stable maintainers, others) follow our recommendations, some kernels will get two of these patches, other kernel versions will get three and some lucky kernels might get all four. Are you confident that the patches can be split apart in this fashion and still produce a good result? After all, we're sending downstream some patch combinations which we didn't test. Also, can you speculate about why these things took so long to discover? Ho hum, complicated. Let's at least slap a Fixes: on [4/4]. My trillion-dollar sidekick suggests a9e443086489 ("hugetlb: disable region_add file_region coalescing"). Our other little friend is talking to us: https://sashiko.dev/#/patchset/20260916-hugetlb-subpool-always-track-used-v3-0-38aae9b5ccdd@google.com I'd like to queue this up promptly because it fixes things. But let's seek additional review input and argue with Sashiko before taking that step.