From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9063E322B90 for ; Thu, 15 Jan 2026 20:43:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768509781; cv=none; b=mWTePeohscUK2NhLiJ7qGvWMB9Gjy5l7wxy3nnTEjVZyUHuLUL7jyfanFoB19rPQ/7bNrW023DoiXVmj2d8ygAlTGldmNQN3FaHzH0yYGEmHd1hB82OlKVdWMpqVaoVfRmb1nHkmjCCbPOv86KZcYVpzQ9ydXWs/rqVfxEGi5hg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768509781; c=relaxed/simple; bh=rkmrkZwHKI0uV2MWHOCpMDsFAeLDcI5WrDtYy1nryic=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qobVyoL8b/5A4A7DUMn+59zEOKZryQKRMPDT5gNB4D3aWWXzc5gvR6BLYCCUKDyUeJ0kkGXHnRYUQCtawRgDIHFN9oP0cimyNjN1OxH2dZlyFZgqDEWWYlfxbhJOmUPHW6uhbkRb1lrSkTyZmpvOHvtw4qTE+7BluPgeyb3ekHI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s0wkhBtk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s0wkhBtk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC162C116D0; Thu, 15 Jan 2026 20:42:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768509781; bh=rkmrkZwHKI0uV2MWHOCpMDsFAeLDcI5WrDtYy1nryic=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=s0wkhBtk4VGsRPniO41iS5y+tOHZKaU/pyhnV9vlCXwkyybOGkxEE9xhXTjeMLRfq CzuO+72zB6AexagGD/kmCTK41V/uh68LOwXzMjvs1iIMq3SWonYYkAOeLnZ8xBCHeB neZ4aK1kjg62sTc/j/1+ZC09vOTyG3dXDpjNbGUqSH5S8chtlP2q+rVRPdvoj3JWfk d4mjj9G0lRtcrq5wmBSDmngeO0JfZwhmyc14JtG/kgL6/QAv8gMyu7dXV834sdjm9M APQDeFmx/SWdZXay0FH4yOj80IwBNSIm2fCvmv76OtosdeLpmwsgrLSnQqH8u227dw Z5jgbrN7Oxxig== Message-ID: <671528cf-6fe8-464d-8028-ecd5822f9053@kernel.org> Date: Thu, 15 Jan 2026 21:42:53 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm/page_alloc: only free healthy pages in high-order has_hwpoisoned folio To: Jiaqi Yan , jackmanb@google.com, hannes@cmpxchg.org, linmiaohe@huawei.com, ziy@nvidia.com, harry.yoo@oracle.com, willy@infradead.org Cc: nao.horiguchi@gmail.com, lorenzo.stoakes@oracle.com, william.roche@oracle.com, tony.luck@intel.com, wangkefeng.wang@huawei.com, jane.chu@oracle.com, akpm@linux-foundation.org, osalvador@suse.de, muchun.song@linux.dev, rientjes@google.com, duenwen@google.com, jthoughton@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com References: <20260112004923.888429-1-jiaqiyan@google.com> <20260112004923.888429-3-jiaqiyan@google.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/12/26 01:49, Jiaqi Yan wrote: > At the end of dissolve_free_hugetlb_folio(), a free HugeTLB folio > becomes non-HugeTLB, and it is released to buddy allocator > as a high-order folio, e.g. a folio that contains 262144 pages > if the folio was a 1G HugeTLB hugepage. > > This is problematic if the HugeTLB hugepage contained HWPoison > subpages. In that case, since buddy allocator does not check > HWPoison for non-zero-order folio, the raw HWPoison page can > be given out with its buddy page and be re-used by either > kernel or userspace. Do we really have to have all that complexity in free_frozen_pages(). Can't we hook into __update_and_free_hugetlb_folio() and just free the chunks there? > > Memory failure recovery (MFR) in kernel does attempt to take > raw HWPoison page off buddy allocator after > dissolve_free_hugetlb_folio(). However, there is always a time > window between dissolve_free_hugetlb_folio() frees a HWPoison > high-order folio to buddy allocator and MFR takes HWPoison > raw page off buddy allocator. I wonder whether marking the pageblock as isolated before freeing it could work? In that case, nobody will be able to allocate the page before we un-isolate it. Just a thought: but when you are dealing with a possible race, you can avoid that race by prohibiting the intermediate allocation from happening in the first place. Also, this is a lot of complexity. Was this issue already hit in the past or is it purely theoretical? -- Cheers David