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 11F86C79FB6 for ; Wed, 9 Sep 2026 22:50:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A765F6B008A; Wed, 9 Sep 2026 18:50:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9D9E86B008C; Wed, 9 Sep 2026 18:50:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 87CDF6B0092; Wed, 9 Sep 2026 18:50:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 582C36B008A for ; Wed, 9 Sep 2026 18:50:09 -0400 (EDT) Received: from smtpin18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id BCBF51A038D for ; Wed, 9 Sep 2026 22:50:08 +0000 (UTC) X-FDA: 85195718496.18.85CCEDD Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf15.hostedemail.com (Postfix) with ESMTP id 06C31A0003 for ; Wed, 9 Sep 2026 22:50:06 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=U+PeqIpW; spf=pass (imf15.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=1788994207; b=OdXXvbVRbqwsgCXkbURyWQ5G9YO02j/U5EhtP6w9jryBHCe8ofBRvOLBguUl+KHPvsNyG+ acOPZIiHU37OAJd+5IgY86Uuux3DXJuNkDbLJ6add13bYj5Chv4BYvdJWVTppFsPrx1LvY +9YP4leglCK19utNO0GKRgPAKcp8J6M= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=U+PeqIpW; spf=pass (imf15.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=1788994207; 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=uakFVAIIg+dbHdGGvnXSLW6H1vVCapIuu4+L13nJJjk=; b=s0iFq1FenvqBhpiJSb0tz/cjQLsI3NIJ3dV4/nPqJs1aFp6ltaclj8ie//q8DR2/JmI9WP cY8lqL0u5f0ziKPSZLVXM2T0y+FcLS1pK63iheh4fP2R+WRwq+NglhzuCToYGBgVW2cjp1 NhJHES1sa/C1PkHJGuOVi6DnEWMTHkw= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 8A0DB600CB; Wed, 9 Sep 2026 22:50:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42B7B1F000FF; Wed, 9 Sep 2026 22:50:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788994205; bh=uakFVAIIg+dbHdGGvnXSLW6H1vVCapIuu4+L13nJJjk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=U+PeqIpWC5DBh7q130lXHtII8ntvQj6lTQyojE9Aa4ICHDsKDcddEAQ9+1CLiYlQc x7+ZxQ1yV/yDo+LuIT+OC5chsw2pvOUEhzMvkqoEDtuzInX/VCiD9d2qRnqjPiAo10 TfAJHc5TmbunSfpK8c7oUec5KvYaPajoE1nEE1Sw= Date: Wed, 9 Sep 2026 15:50:03 -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 , 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 v2 0/4] Fix HugeTLB subpool used_hpages tracking Message-Id: <20260909155003.e6c2f4fe3c0bbee3b34578fd@linux-foundation.org> In-Reply-To: <20260909-hugetlb-subpool-always-track-used-v2-0-30c5d83b572a@google.com> References: <20260909-hugetlb-subpool-always-track-used-v2-0-30c5d83b572a@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: rspam12 X-Rspamd-Queue-Id: 06C31A0003 X-Rspam-User: X-Stat-Signature: qxshwsi16ayt8wewup1b1yr85yy4axiu X-HE-Tag: 1788994206-129946 X-HE-Meta: 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 nuxMHhzi INvxfkvP9kr7LU8VeSZXx5kOQf1IKS7GeYEUQTjPIpkJlRKt4Npbaojxszk+dpvCh8xyfGB+WSvcKeLKR76O00/zIDdG08EuTiJlypZpTznpqlZJJMsxbj92QBGVQVca/16oe8RijfAlRKRXj4GySAeLrHOHkV8/bakwUOqIbopBEggGHnJtBkVJ4+R1+hFMYd0AdUUJwhC6IW49RznW1gj20zGPgPpdAdzHNC9BE13Y2/puYtXCJM9S4z32FlGh2E2O/D0sBRXg9tpm/bgbOOu5IaS2AOv2UnTzZ1/uNQu0SgNcbEuJI96lRzSpsnbClVlyrk7GjK3hq4b+qyjlCSmMFYCXDZ6vgWD6lsSGHGzFzizW2lLVu2Wzs6jiYLbhf5gaU2OxpgwnbDPxjoFPQwlOjKinWjPSjF66GP42p4OgQDDaTEyvN35VHd5wiL919dtSBJtFQ0Ub5zsk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 09 Sep 2026 14:49:25 -0700 Ackerley Tng via B4 Relay wrote: > HugeTLB subpools currently only track used_hpages when the user configures > a size limit. > > This is buggy since when there are existing allocations from the subpool > that would have satisfied the minimum reservations, > hugepage_subpool_put_pages() will still restore a reservation to the > subpool. See below for an example of a false reservation. That sounds annoying, although isn't clear how this affects end-users. > In addition, the subpool is considered free prematurely, is freed, and this > ends up causing a use-after-free. That sounds alarming. Do you think it's best for us to submit [1-3] for -stable backporting? Is it feasible to come up with a set of small little fixes to get -stable out of trouble and then to prepare broader updates for our ongoing mainline development? If it's "shut up Andrew you're always saying that" then OK, I can take that :)