From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DFD2022A4E1; Thu, 17 Sep 2026 03:13:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789614791; cv=none; b=qPjjxj917IAmkoj9rQH8HHLxiMHEc04vX8Uum9I4ajsydJaH6OIfCG066RvGcbAVLo9+8CFQxjSwO+8QquQr1Aa4TaHAwbMNexkT9de4KpAOWeg6KbRoqul9S36JmyqYEYd+fH4ABNKX4QW/h22zRw9Cq8SY436j8d+jAn5WQcM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789614791; c=relaxed/simple; bh=FeKcoJ3loGn8FJEmciBgvprU0VZac3yRZ7pwrvMBqgQ=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=uMeT7O7ugOrLiE6L7x5THDYmBYcJi3vYa1ZTxlSusNb2MLBf9CWzgihsLif9yeEQeHp5l9RkcFMBsD5BVBHfJyg/mskAOpxxwEBznvJjmjZDhnjZOvOge9DBLz1gWjS27QOL6acPAZ5mixMv2FksYn7gT7jcxBz8M2TT93Ay2QI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=hBiJNpgS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="hBiJNpgS" 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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.