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]) by smtp.lore.kernel.org (Postfix) with ESMTP id D87FCC5B543 for ; Wed, 4 Jun 2025 10:07:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 74DF86B0317; Wed, 4 Jun 2025 06:07:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 725806B0318; Wed, 4 Jun 2025 06:07:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63BAE6B031A; Wed, 4 Jun 2025 06:07:31 -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 420F76B0317 for ; Wed, 4 Jun 2025 06:07:31 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CB3705DB21 for ; Wed, 4 Jun 2025 10:07:30 +0000 (UTC) X-FDA: 83517291060.23.29F28F2 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf01.hostedemail.com (Postfix) with ESMTP id 54E9940004 for ; Wed, 4 Jun 2025 10:07:28 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=iHPkAJhT; spf=pass (imf01.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1749031648; 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=7PRfniGheLvssRHrIJEaU1qt06uo8ioIfyXuvxIrE6A=; b=FtASUclFbQrSia6dlEZwqowKPxaivhOJqCS6ZmmsSlHlR2/dwHOpdkeCqZNs9kE9/uMm7z 2n+Sg5UoDeV6tF/T/TQ3Vy7l5q7Mg2GcMafgLiuj1UyQsUYDWAto6tlNMvb8i6GfD0OmJa vbItZ6ELzEjc/B8El056oTbIJcIlwi0= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=iHPkAJhT; spf=pass (imf01.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1749031648; a=rsa-sha256; cv=none; b=qgkgpvSGjN4mdf/FM+EJzVdqBrPRhJI+DNMBcFIGKNkA3WP5UWnysheTUhvN3yEkRSI4ZD AgGZi08NrBnFyPRe6fp+lq1Z84Bk/q44MNk+bKIXvjxcxlL+2J4i0CvQrIubmgJ3PmGia/ wwsLHpmlPYcnThYeJvq5vxCdDlw7sZ4= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749031647; h=from:from: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:autocrypt:autocrypt; bh=7PRfniGheLvssRHrIJEaU1qt06uo8ioIfyXuvxIrE6A=; b=iHPkAJhT4iGibL4T9eIztp07fwHH4uFNeKJcgFkDhB/suaMQCxAwVHkrXORXQizguHefI4 y/N2HLOkSm7FSACvF6Uw5wtewV7CfC0/+fH75rez+8JFJoqAZs7d73lQNi8Bf7io+QdxJ1 6dw4fw9F8R6BDKmZzSD2H3FtUarQfyc= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-76-PQtol_glPpiIR8W9KLY47g-1; Wed, 04 Jun 2025 06:07:24 -0400 X-MC-Unique: PQtol_glPpiIR8W9KLY47g-1 X-Mimecast-MFC-AGG-ID: PQtol_glPpiIR8W9KLY47g_1749031643 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-450dada0f83so38734685e9.0 for ; Wed, 04 Jun 2025 03:07:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749031643; x=1749636443; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=7PRfniGheLvssRHrIJEaU1qt06uo8ioIfyXuvxIrE6A=; b=FM4Aaj5FjwPOZ/fKJ8hdgFqnsdMfWOq9/cCPrcGScq3rJAwaFOLdlceG8Y00lNt4wc MqB8+GN+WEos4vdcdGK/3Xaunxals8V2okgg7thMKCQaxP4MY3HxMxH/2HMK9xoGIKUw Yaj8DFCtE/TO7ZCjUn4dOIwoXRLLYQ5/7xgumR1ncDT9PWWoea5M/lK46o188X4FWWfi znEJDpGQV0ymGjM94t7rp0Gk6HUTsSp0ThWKzkTT1hTdSIJI1mGHRzLGuCbKmR6Tyu0f UutsNHgHB5vWXkoc2PlllZ318oGb1FxBj/6F/dLyVxa4478ifiQF3AvqEhu8Shh1aDVE xzCA== X-Forwarded-Encrypted: i=1; AJvYcCUQ/m4intB+PPkE75qMvvmBdVhKRit3rQkmGwm2RV9+bt5lCw7mA3ZRnL3slgvIhkqk59+RkgyFqA==@kvack.org X-Gm-Message-State: AOJu0YxX9EQhOGcUKh33+j6zgGksFa8WPgrVp4KgNZoiMgHxJ/RMN/k3 i0giZ5kgRyPZUOQxWpb3wglMm77q7C3FA5bUWbg+tFOOOQKPn96lijDxeCSohDte4rHXLl+Dgrx NmU+RGCf0QTFKRzvYQ9zA714a/c7htRE1hwhQRqGJm7nEjVX3jY7Y X-Gm-Gg: ASbGnctnlR5C46hGtPoO/VcsZud8NXV6XMYD4mtDUJuAQkP/o3OF9EPt17rkLIgz0lX t3lq0luIGBWd0DtpQBRv9b69cVilJaZYGjISc0eOAmXW+FfK/Jw9maqtOCE61YBMEhmrlZ2bqj2 lx12z3NCvnGgsaNldvGCSkVcmZTimJcJKFWjCh8UM22vKYlARVb3QVk3uC/kv+ijLIrgGgHBGn9 Jna2x7Z6n/UgtIwaFxZW4DZkO8Vl+evA0ecIsw6/VUisypLHmRpm3ZU6MUTETQJ1kmz8SQgy/x2 8XsqyrWUkDz9PhugVC+yR5qvFLeGwEvgeZ/FQ9j0nw7BV5N8wUn7CXC8xHGa2i3PVYTkLPXf7Vs NkUJkub3IqX75wp/iJJHGWcZfbFbJgU8rF1bbZsQ= X-Received: by 2002:a05:600c:a015:b0:450:d37c:9fc8 with SMTP id 5b1f17b1804b1-451f0a74191mr18412195e9.13.1749031643159; Wed, 04 Jun 2025 03:07:23 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG7o2bEYM4OLlTeV0JBA6sp6f4ZXgEdhRDuQC/nWLoEHV+qeqnF/gO2YE9gGAKeTmJLS62Qxg== X-Received: by 2002:a05:600c:a015:b0:450:d37c:9fc8 with SMTP id 5b1f17b1804b1-451f0a74191mr18411865e9.13.1749031642639; Wed, 04 Jun 2025 03:07:22 -0700 (PDT) Received: from ?IPV6:2003:d8:2f1b:b800:6fdb:1af2:4fbd:1fdf? (p200300d82f1bb8006fdb1af24fbd1fdf.dip0.t-ipconnect.de. [2003:d8:2f1b:b800:6fdb:1af2:4fbd:1fdf]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-450d8006613sm201595465e9.28.2025.06.04.03.07.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Jun 2025 03:07:22 -0700 (PDT) Message-ID: Date: Wed, 4 Jun 2025 12:07:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: gup: fail migration when no migratable page to prevent CMA pinning To: Hyesoo Yu Cc: janghyuck.kim@samsung.com, zhaoyang.huang@unisoc.com, jaewon31.kim@gmail.com, Andrew Morton , Jason Gunthorpe , John Hubbard , Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250604095049.4052078-1-hyesoo.yu@samsung.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250604095049.4052078-1-hyesoo.yu@samsung.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: IHqOxkhtd1qU9rjf01iouTq6DBn5VDaN5HnkvxM0GP4_1749031643 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: ir8kxugg74x1awxqbtr3wrn73zgkw8tw X-Rspamd-Queue-Id: 54E9940004 X-Rspamd-Server: rspam11 X-HE-Tag: 1749031648-437315 X-HE-Meta: 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 wAbELt9M 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04.06.25 11:50, Hyesoo Yu wrote: > Commit 1aaf8c122918 ("mm: gup: fix infinite loop within __get_longterm_locked") > caused CMA pages to become pinned in some cases when handling longterm GUP. > This happened because migration would return success immediately if no pages > were in the movable_page_list, without retrying. > > However, CMA pages can be temporarily off the LRU (e.g., in pagevecs), and A better example might be concurrent isolation. Just imagine two of these longterm pinnings racing. > therefore not appear in movable_page_list, even though they can be migrated > later. Before commit 1aaf8c, the kernel would retry migration in such cases, > which helped avoid accidental CMA pinning. > > The commit 1aaf8c aimed to support an out-of-tree use case (like pKVM), where > longterm GUP was applied to non-LRU CMA pages. But allowing CMA pinning > in general for this corner case could lead to more fragmentation and > reliability issues. So this patch prevents that. > > Instead of retrying, this patch explicitly fails the migration attempt > (-EBUSY) if no movable pages are found and unpinnable pages remain. > This avoids infinite loops and gives user a clear signal to retry, > rather then spinning inside kernel. Hmmm, that means we will return EBUSY to the caller. Are all users actually prepared to deal with that? So far we only returned EBUSY in this corner-case migrate_device_coherent_folio() that most callers never actually trigger. Maybe we should do EAGAIN for now (old way of doing it?), and look into doing EBUSY separately. > > Fixes: 1aaf8c122918 ("mm: gup: fix infinite loop within __get_longterm_locked") > Signed-off-by: Hyesoo Yu > --- > mm/gup.c | 49 ++++++++++++++++++++++++++----------------------- > 1 file changed, 26 insertions(+), 23 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index e065a49842a8..446938aedcc9 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2303,12 +2303,13 @@ static void pofs_unpin(struct pages_or_folios *pofs) > /* > * Returns the number of collected folios. Return value is always >= 0. > */ Comment should be removed. > -static void collect_longterm_unpinnable_folios( > +static bool collect_longterm_unpinnable_folios( > struct list_head *movable_folio_list, > struct pages_or_folios *pofs) > { > struct folio *prev_folio = NULL; > bool drain_allow = true; > + bool any_unpinnable = false; > unsigned long i; > > for (i = 0; i < pofs->nr_entries; i++) { > @@ -2321,6 +2322,8 @@ static void collect_longterm_unpinnable_folios( > if (folio_is_longterm_pinnable(folio)) > continue; > > + any_unpinnable = true; > + > if (folio_is_device_coherent(folio)) > continue; > > @@ -2342,6 +2345,8 @@ static void collect_longterm_unpinnable_folios( > NR_ISOLATED_ANON + folio_is_file_lru(folio), > folio_nr_pages(folio)); > } > + > + return any_unpinnable; > } > > /* > @@ -2353,8 +2358,13 @@ static int > migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, > struct pages_or_folios *pofs) > { > - int ret; > + int ret = -EAGAIN; > unsigned long i; > + struct migration_target_control mtc = { > + .nid = NUMA_NO_NODE, > + .gfp_mask = GFP_USER | __GFP_NOWARN, > + .reason = MR_LONGTERM_PIN, > + }; Reverse xmas tree while we're at it. But, can we do this cleanup here separately, and not as part of the fix? > > for (i = 0; i < pofs->nr_entries; i++) { > struct folio *folio = pofs_get_folio(pofs, i); > @@ -2370,6 +2380,7 @@ migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, > gup_put_folio(folio, 1, FOLL_PIN); > > if (migrate_device_coherent_folio(folio)) { > + pofs_unpin(pofs); > ret = -EBUSY; > goto err; > } > @@ -2388,27 +2399,11 @@ migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, > pofs_clear_entry(pofs, i); > } > > - if (!list_empty(movable_folio_list)) { > - struct migration_target_control mtc = { > - .nid = NUMA_NO_NODE, > - .gfp_mask = GFP_USER | __GFP_NOWARN, > - .reason = MR_LONGTERM_PIN, > - }; > - > - if (migrate_pages(movable_folio_list, alloc_migration_target, > - NULL, (unsigned long)&mtc, MIGRATE_SYNC, > - MR_LONGTERM_PIN, NULL)) { > - ret = -ENOMEM; > - goto err; > - } > - } > - > - putback_movable_pages(movable_folio_list); > - > - return -EAGAIN; > + if (migrate_pages(movable_folio_list, alloc_migration_target, NULL, > + (unsigned long)&mtc, MIGRATE_SYNC, MR_LONGTERM_PIN, NULL)) > + ret = -ENOMEM; > > err: > - pofs_unpin(pofs); > putback_movable_pages(movable_folio_list); > > return ret; > @@ -2417,11 +2412,19 @@ migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, > static long > check_and_migrate_movable_pages_or_folios(struct pages_or_folios *pofs) > { > + bool any_unpinnable; > + > LIST_HEAD(movable_folio_list); > > - collect_longterm_unpinnable_folios(&movable_folio_list, pofs); > - if (list_empty(&movable_folio_list)) > + any_unpinnable = collect_longterm_unpinnable_folios(&movable_folio_list, pofs); > + > + if (list_empty(&movable_folio_list)) { > + if (any_unpinnable) { /* * If we find any longterm unpinnable page that we failed to * isolated for migration, it might be because someone else * concurrently isolated it. Make the caller retry until it * succeeds. */ > + pofs_unpin(pofs); > + return -EBUSY; > + } > return 0; > + } > > return migrate_longterm_unpinnable_folios(&movable_folio_list, pofs); > } -- Cheers, David / dhildenb