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 7ED0AC47089 for ; Fri, 2 Dec 2022 12:07:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EBFA96B0074; Fri, 2 Dec 2022 07:07:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E48086B0075; Fri, 2 Dec 2022 07:07:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C9ADB6B0078; Fri, 2 Dec 2022 07:07:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id AEFAD6B0074 for ; Fri, 2 Dec 2022 07:07:11 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 755791C4305 for ; Fri, 2 Dec 2022 12:07:11 +0000 (UTC) X-FDA: 80197240662.22.EA379A3 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf17.hostedemail.com (Postfix) with ESMTP id 2DCE740013 for ; Fri, 2 Dec 2022 12:07:09 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=EsfZ77a9; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf17.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669982830; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=981M8OmF9Q0GMUAkG+oR6bVpBvuwOzSSVaWAm2iCSmQ=; b=UwUMAh+0w/V4XPIc32WznMmb4oqXvu+2xZQrMlBc/PmWgQYTBX6ZhTcFffjyvRJ2y8IM2R ZSjsIT4Gw3GFmZvBtrMvuufHTolFSoTcuLboTO1IwhJC0pEPWi5p84Kg/RDTXy2Rhx8tTi A72U3guMdyA4GBzMM5MWrADXGKm5MIg= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=EsfZ77a9; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf17.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669982830; a=rsa-sha256; cv=none; b=T5GI9LuOr62Y+/w/19eFwN9BPTFzswWyGNEtWiJkIyN3mqGVc3bz/P+LXuqHo7CTF6FXgq GiuIboJKCNuc+xUaJy1C0qoMdUwsY3NgucE2XG9BFuds0CMwcZ2a8Cn5XTswrZUcByoAp+ PVP7vDm49VUmBJ+HH3P9BfCZXkBrbb8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669982829; 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: in-reply-to:in-reply-to:references:references; bh=981M8OmF9Q0GMUAkG+oR6bVpBvuwOzSSVaWAm2iCSmQ=; b=EsfZ77a9WrYwlTvS+2zBEWNk9JvhkockCVYj6c3kfAOClv/L9lOzkGudlNIqwl7A474sJy 9tfepnQP/EVQsW5ejAyZITWSI3W6dW7M7XtfDhC/S7rVVLr8b6WAMABXh8TbgeNtpgEgJT qmzaIlMY9Ubtl8YgMXRu4xjOxnrfVa8= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-284-T_eTWGl3Nwm6vWpiTyDZFg-1; Fri, 02 Dec 2022 07:07:05 -0500 X-MC-Unique: T_eTWGl3Nwm6vWpiTyDZFg-1 Received: by mail-wm1-f70.google.com with SMTP id c126-20020a1c3584000000b003cfffcf7c1aso4060984wma.0 for ; Fri, 02 Dec 2022 04:07:05 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:subject:organization:references:cc:to:from :content-language:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=o/hK9+cXmqXiMjdThM+s0BtmMRZhVBhPO7TEP7tZb+w=; b=E29W96QjovltdY6eQftsf8i4rSo3+i3DiRtf/pS1J/1cn0uldQuDmumBAFN7tPxVub 3rQbe3KVBq5kJa2ey4N0BtztOfB+D58l665nSqbK+b1GmyGWnrvAXJEjWIhqTBWpBRX2 6JfLEx82mLsMMllBsTNKIl1Fq4OQ6bl4HnHt54tDLhdOrhpEga63wv4OXL8fNR/1ukC6 kyz9DO221Gzb4fJMoTKeo0we5DtGYwiXd5ykekqCT5NscrfEgca2yAy/U3DX4zvHf7Oi Emb2x7jaOjWxvHG9fGqqsflWtciPssm3zYki+s02EfQiDQz69QZi/8HDERr8qQ4AxsDQ l+Mw== X-Gm-Message-State: ANoB5pl7unZBLz5hUheMTUwK51/X0edf/Y87PvSzVGJFTGPuT2FMmLf9 BE80ILRdQwBycT4GcRvoBRhUuvFWUTiJ5lh2FZhEM8bSzMx7G5j4gutZ5iHX6hb7lU/2u9iPf2F sqRXuOnH8iWg= X-Received: by 2002:a5d:4acf:0:b0:242:4c45:d32d with SMTP id y15-20020a5d4acf000000b002424c45d32dmr72968wrs.428.1669982824658; Fri, 02 Dec 2022 04:07:04 -0800 (PST) X-Google-Smtp-Source: AA0mqf6AZLFtnbPa4YXwrAOL6nOHxreMKDx8qvBgFT7OAWT/I/C1FArtJMzvJcvert8qKFNYkT9GSw== X-Received: by 2002:a5d:4acf:0:b0:242:4c45:d32d with SMTP id y15-20020a5d4acf000000b002424c45d32dmr72947wrs.428.1669982824308; Fri, 02 Dec 2022 04:07:04 -0800 (PST) Received: from ?IPV6:2003:cb:c703:7a00:852e:72cd:ed76:d72f? (p200300cbc7037a00852e72cded76d72f.dip0.t-ipconnect.de. [2003:cb:c703:7a00:852e:72cd:ed76:d72f]) by smtp.gmail.com with ESMTPSA id 11-20020a05600c228b00b003d01b84e9b2sm8092605wmf.27.2022.12.02.04.07.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Dec 2022 04:07:03 -0800 (PST) Message-ID: <222fc0b2-6ec0-98e7-833f-ea868b248446@redhat.com> Date: Fri, 2 Dec 2022 13:07:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 From: David Hildenbrand To: Andrew Morton Cc: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mike Rapoport , Nadav Amit , Andrea Arcangeli , Ives van Hoorne , Axel Rasmussen , Alistair Popple , stable@vger.kernel.org References: <20221114000447.1681003-1-peterx@redhat.com> <20221114000447.1681003-2-peterx@redhat.com> <5ddf1310-b49f-6e66-a22a-6de361602558@redhat.com> <20221130142425.6a7fdfa3e5954f3c305a77ee@linux-foundation.org> <20221201143058.80296541cc6802d1e5990033@linux-foundation.org> Organization: Red Hat Subject: Re: [PATCH v3 1/2] mm/migrate: Fix read-only page got writable when recover pte In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="------------ApHjnS14u0ZxFpWQKPOgTgNr" Content-Language: en-US X-Stat-Signature: g7mr4dfhcujttgnhadfteeu7kxd96cko X-Spamd-Result: default: False [0.30 / 9.00]; BAYES_HAM(-3.00)[100.00%]; MIME_BAD_ATTACHMENT(1.60)[c:text/x-csrc]; SUSPICIOUS_RECIPS(1.50)[]; MIME_BASE64_TEXT_BOGUS(1.00)[]; DMARC_POLICY_ALLOW(-0.50)[redhat.com,none]; R_DKIM_ALLOW(-0.20)[redhat.com:s=mimecast20190719]; R_SPF_ALLOW(-0.20)[+ip4:170.10.133.0/24]; MIME_GOOD(-0.10)[multipart/mixed,text/plain,text/x-csrc]; MIME_BASE64_TEXT(0.10)[]; RCVD_NO_TLS_LAST(0.10)[]; RCPT_COUNT_SEVEN(0.00)[11]; TAGGED_RCPT(0.00)[]; FROM_HAS_DN(0.00)[]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; PREVIOUSLY_DELIVERED(0.00)[linux-mm@kvack.org]; TO_DN_SOME(0.00)[]; HAS_ATTACHMENT(0.00)[]; DKIM_TRACE(0.00)[redhat.com:+]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_THREE(0.00)[4]; HAS_ORG_HEADER(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:+]; FROM_EQ_ENVFROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[] X-Rspamd-Queue-Id: 2DCE740013 X-Rspamd-Server: rspam08 X-Rspam-User: X-HE-Tag: 1669982829-313191 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: This is a multi-part message in MIME format. --------------ApHjnS14u0ZxFpWQKPOgTgNr Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 02.12.22 12:03, David Hildenbrand wrote: > On 01.12.22 23:30, Andrew Morton wrote: >> On Thu, 1 Dec 2022 16:42:52 +0100 David Hildenbrand wrote: >> >>> On 01.12.22 16:28, Peter Xu wrote: >>>> >>>> I didn't reply here because I have already replied with the question in >>>> previous version with a few attempts. Quotting myself: >>>> >>>> https://lore.kernel.org/all/Y3KgYeMTdTM0FN5W@x1n/ >>>> >>>> The thing is recovering the pte into its original form is the >>>> safest approach to me, so I think we need justification on why it's >>>> always safe to set the write bit. >>>> >>>> I've also got another longer email trying to explain why I think it's the >>>> other way round to be justfied, rather than justifying removal of the write >>>> bit for a read migration entry, here: >>>> >>> >>> And I disagree for this patch that is supposed to fix this hunk: >>> >>> >>> @@ -243,11 +243,15 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, >>> entry = pte_to_swp_entry(*pvmw.pte); >>> if (is_write_migration_entry(entry)) >>> pte = maybe_mkwrite(pte, vma); >>> + else if (pte_swp_uffd_wp(*pvmw.pte)) >>> + pte = pte_mkuffd_wp(pte); >>> >>> if (unlikely(is_zone_device_page(new))) { >>> if (is_device_private_page(new)) { >>> entry = make_device_private_entry(new, pte_write(pte)); >>> pte = swp_entry_to_pte(entry); >>> + if (pte_swp_uffd_wp(*pvmw.pte)) >>> + pte = pte_mkuffd_wp(pte); >>> } >>> } >> >> David, I'm unclear on what you mean by the above. Can you please >> expand? >> >>> >>> There is really nothing to justify the other way around here. >>> If it's broken fix it independently and properly backport it independenty. >>> >>> But we don't know about any such broken case. >>> >>> I have no energy to spare to argue further ;) >> >> This is a silent data loss bug, which is about as bad as it gets. >> Under obscure conditions, fortunately. But please let's keep working >> it. Let's aim for something minimal for backporting purposes. We can >> revisit any cleanliness issues later. > > Okay, you activated my energy reserves. > >> >> David, do you feel that the proposed fix will at least address the bug >> without adverse side-effects? > > Usually, when I suspect something is dodgy I unconsciously push back > harder than I usually would. > > I just looked into the issue once again and realized that this patch > here (and also my alternative proposal) most likely tackles the > more-generic issue from the wrong direction. I found yet another such > bug (most probably two, just too lazy to write another reproducer). > Migration code does the right thing here -- IMHO -- and the issue should > be fixed differently. > > I'm testing an alternative patch right now and will share it later > today, along with a reproducer. > mprotect() reproducer attached. -- Thanks, David / dhildenb --------------ApHjnS14u0ZxFpWQKPOgTgNr Content-Type: text/x-csrc; charset=UTF-8; name="uffd-wp-mprotect.c" Content-Disposition: attachment; filename="uffd-wp-mprotect.c" Content-Transfer-Encoding: base64 I2RlZmluZSBfR05VX1NPVVJDRQojaW5jbHVkZSA8c3RkaW8uaD4KI2luY2x1ZGUgPHN0ZGxpYi5o PgojaW5jbHVkZSA8c3RyaW5nLmg+CiNpbmNsdWRlIDxmY250bC5oPgojaW5jbHVkZSA8dW5pc3Rk Lmg+CiNpbmNsdWRlIDxlcnJuby5oPgojaW5jbHVkZSA8cG9sbC5oPgojaW5jbHVkZSA8cHRocmVh ZC5oPgojaW5jbHVkZSA8c3lzL21tYW4uaD4KI2luY2x1ZGUgPHN5cy9zeXNjYWxsLmg+CiNpbmNs dWRlIDxzeXMvaW9jdGwuaD4KI2luY2x1ZGUgPGxpbnV4L21lbWZkLmg+CiNpbmNsdWRlIDxsaW51 eC91c2VyZmF1bHRmZC5oPgoKc2l6ZV90IHBhZ2VzaXplOwppbnQgdWZmZDsKCnN0YXRpYyB2b2lk ICp1ZmZkX3RocmVhZF9mbih2b2lkICphcmcpCnsKCXN0YXRpYyBzdHJ1Y3QgdWZmZF9tc2cgbXNn OwoJc3NpemVfdCBucmVhZDsKCgl3aGlsZSAoMSkgewoJCXN0cnVjdCBwb2xsZmQgcG9sbGZkOwoJ CWludCBucmVhZHk7CgoJCXBvbGxmZC5mZCA9IHVmZmQ7CgkJcG9sbGZkLmV2ZW50cyA9IFBPTExJ TjsKCQlucmVhZHkgPSBwb2xsKCZwb2xsZmQsIDEsIC0xKTsKCQlpZiAobnJlYWR5ID09IC0xKSB7 CgkJCWZwcmludGYoc3RkZXJyLCAicG9sbCgpIGZhaWxlZDogJWRcbiIsIGVycm5vKTsKCQkJZXhp dCgxKTsKCQl9CgoJCW5yZWFkID0gcmVhZCh1ZmZkLCAmbXNnLCBzaXplb2YobXNnKSk7CgkJaWYg KG5yZWFkIDw9IDApCgkJCWNvbnRpbnVlOwoKCQlpZiAobXNnLmV2ZW50ICE9IFVGRkRfRVZFTlRf UEFHRUZBVUxUIHx8CgkJICAgICEobXNnLmFyZy5wYWdlZmF1bHQuZmxhZ3MgJiBVRkZEX1BBR0VG QVVMVF9GTEFHX1dQKSkgewoJCQlwcmludGYoIkZBSUw6IHdyb25nIHVmZmQtd3AgZXZlbnQgZmly ZWRcbiIpOwoJCQlleGl0KDEpOwoJCX0KCgkJcHJpbnRmKCJQQVNTOiB1ZmZkLXdwIGZpcmVkXG4i KTsKCQlleGl0KDApOwoJfQp9CgpzdGF0aWMgaW50IHNldHVwX3VmZmQoY2hhciAqbWFwKQp7Cglz dHJ1Y3QgdWZmZGlvX2FwaSB1ZmZkaW9fYXBpOwoJc3RydWN0IHVmZmRpb19yZWdpc3RlciB1ZmZk aW9fcmVnaXN0ZXI7CglzdHJ1Y3QgdWZmZGlvX3JhbmdlIHVmZmRfcmFuZ2U7CglwdGhyZWFkX3Qg dGhyZWFkOwoKCXVmZmQgPSBzeXNjYWxsKF9fTlJfdXNlcmZhdWx0ZmQsCgkJICAgICAgIE9fQ0xP RVhFQyB8IE9fTk9OQkxPQ0sgfCBVRkZEX1VTRVJfTU9ERV9PTkxZKTsKCWlmICh1ZmZkIDwgMCkg ewoJCWZwcmludGYoc3RkZXJyLCAic3lzY2FsbCgpIGZhaWxlZDogJWRcbiIsIGVycm5vKTsKCQly ZXR1cm4gLWVycm5vOwoJfQoKCXVmZmRpb19hcGkuYXBpID0gVUZGRF9BUEk7Cgl1ZmZkaW9fYXBp LmZlYXR1cmVzID0gVUZGRF9GRUFUVVJFX1BBR0VGQVVMVF9GTEFHX1dQOwoJaWYgKGlvY3RsKHVm ZmQsIFVGRkRJT19BUEksICZ1ZmZkaW9fYXBpKSA8IDApIHsKCQlmcHJpbnRmKHN0ZGVyciwgIlVG RkRJT19BUEkgZmFpbGVkOiAlZFxuIiwgZXJybm8pOwoJCXJldHVybiAtZXJybm87Cgl9CgoJaWYg KCEodWZmZGlvX2FwaS5mZWF0dXJlcyAmIFVGRkRfRkVBVFVSRV9QQUdFRkFVTFRfRkxBR19XUCkp IHsKCQlmcHJpbnRmKHN0ZGVyciwgIlVGRkRfRkVBVFVSRV9XUklURVBST1RFQ1QgbWlzc2luZ1xu Iik7CgkJcmV0dXJuIC1FTk9TWVM7Cgl9CgoJdWZmZGlvX3JlZ2lzdGVyLnJhbmdlLnN0YXJ0ID0g KHVuc2lnbmVkIGxvbmcpIG1hcDsKCXVmZmRpb19yZWdpc3Rlci5yYW5nZS5sZW4gPSBwYWdlc2l6 ZTsKCXVmZmRpb19yZWdpc3Rlci5tb2RlID0gVUZGRElPX1JFR0lTVEVSX01PREVfV1A7CglpZiAo aW9jdGwodWZmZCwgVUZGRElPX1JFR0lTVEVSLCAmdWZmZGlvX3JlZ2lzdGVyKSA8IDApIHsKCQlm cHJpbnRmKHN0ZGVyciwgIlVGRkRJT19SRUdJU1RFUiBmYWlsZWQ6ICVkXG4iLCBlcnJubyk7CgkJ cmV0dXJuIC1lcnJubzsKCX0KCglwdGhyZWFkX2NyZWF0ZSgmdGhyZWFkLCBOVUxMLCB1ZmZkX3Ro cmVhZF9mbiwgTlVMTCk7CgoJcmV0dXJuIDA7Cn0KCmludCBtYWluKGludCBhcmdjLCBjaGFyICoq YXJndikKewoJc3RydWN0IHVmZmRpb193cml0ZXByb3RlY3QgdWZmZF93cml0ZXByb3RlY3Q7Cglj aGFyICptYXA7CglpbnQgZmQ7CgoJcGFnZXNpemUgPSBnZXRwYWdlc2l6ZSgpOwoJZmQgPSBtZW1m ZF9jcmVhdGUoInRlc3QiLCAwKTsKCWlmIChmZCA8IDApIHsKCQlmcHJpbnRmKHN0ZGVyciwgIm1l bWZkX2NyZWF0ZSgpIGZhaWxlZFxuIik7CgkJcmV0dXJuIC1lcnJubzsKCX0KCWlmIChmdHJ1bmNh dGUoZmQsIHBhZ2VzaXplKSkgewoJCWZwcmludGYoc3RkZXJyLCAiZnRydW5jYXRlKCkgZmFpbGVk XG4iKTsKCQlyZXR1cm4gLWVycm5vOwoJfQoKCS8qIFN0YXJ0IG91dCB3aXRob3V0IHdyaXRlIHBy b3RlY3Rpb24uICovCgltYXAgPSBtbWFwKE5VTEwsIHBhZ2VzaXplLCBQUk9UX1JFQUR8UFJPVF9X UklURSwgTUFQX1NIQVJFRCwgZmQsIDApOwoJaWYgKG1hcCA9PSBNQVBfRkFJTEVEKSB7CgkJZnBy aW50ZihzdGRlcnIsICJtbWFwKCkgZmFpbGVkXG4iKTsKCQlyZXR1cm4gLWVycm5vOwoJfQoKCWlm IChzZXR1cF91ZmZkKG1hcCkpCgkJcmV0dXJuIDE7CgoJLyogUG9wdWxhdGUgYSBwYWdlIC4uLiAq LwoJbWVtc2V0KG1hcCwgMCwgcGFnZXNpemUpOwoKCS8qIC4uLiBhbmQgd3JpdGUtcHJvdGVjdCBp dCB1c2luZyB1ZmZkLXdwLiAqLwoJdWZmZF93cml0ZXByb3RlY3QucmFuZ2Uuc3RhcnQgPSAodW5z aWduZWQgbG9uZykgbWFwOwoJdWZmZF93cml0ZXByb3RlY3QucmFuZ2UubGVuID0gcGFnZXNpemU7 Cgl1ZmZkX3dyaXRlcHJvdGVjdC5tb2RlID0gVUZGRElPX1dSSVRFUFJPVEVDVF9NT0RFX1dQOwoJ aWYgKGlvY3RsKHVmZmQsIFVGRkRJT19XUklURVBST1RFQ1QsICZ1ZmZkX3dyaXRlcHJvdGVjdCkp IHsKCQlmcHJpbnRmKHN0ZGVyciwgIlVGRkRJT19XUklURVBST1RFQ1QgZmFpbGVkOiAlZFxuIiwg ZXJybm8pOwoJCXJldHVybiAtZXJybm87Cgl9CgoJLyogV3JpdGUtcHJvdGVjdCB0aGUgd2hvbGUg bWFwcGluZyB0ZW1wb3JhcmlseS4gKi8KCW1wcm90ZWN0KG1hcCwgcGFnZXNpemUsIFBST1RfUkVB RCk7CgltcHJvdGVjdChtYXAsIHBhZ2VzaXplLCBQUk9UX1JFQUR8UFJPVF9XUklURSk7CgoJLyog VGVzdCBpZiB1ZmZkLXdwIGZpcmVzLiAqLwoJbWVtc2V0KG1hcCwgMSwgcGFnZXNpemUpOwoKCXBy aW50ZigiRkFJTDogdWZmZC13cCBkaWQgbm90IGZpcmVcbiIpOwoJcmV0dXJuIDE7Cn0K --------------ApHjnS14u0ZxFpWQKPOgTgNr--