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[91.12.100.160]) by smtp.gmail.com with ESMTPSA id o28sm22489467wms.14.2021.08.11.02.35.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Aug 2021 02:35:34 -0700 (PDT) Subject: Re: [PATCH] memblock: Check memory add/cap ordering To: Geert Uytterhoeven , Mike Rapoport , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: From: David Hildenbrand Organization: Red Hat Message-ID: <1c4cb6e9-2ca9-9738-9706-28ff94f8fdcc@redhat.com> Date: Wed, 11 Aug 2021 11:35:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="QhQ4/4Wd"; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf24.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=david@redhat.com X-Stat-Signature: dwn6i1amiwet8df5rimtysqyobh7nsfc X-Rspamd-Queue-Id: DC0F2B004DF0 X-Rspamd-Server: rspam01 X-HE-Tag: 1628674539-63798 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: On 11.08.21 10:55, Geert Uytterhoeven wrote: > For memblock_cap_memory_range() to work properly, it should be called > after memory is detected and added to memblock with memblock_add() or > memblock_add_node(). If memblock_cap_memory_range() would be called > before memory is registered, we may silently corrupt memory later > because the crash kernel will see all memory as available. > > Print a warning and bail out if ordering is not satisfied. > > Suggested-by: Mike Rapoport > Signed-off-by: Geert Uytterhoeven > --- > mm/memblock.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 57a9849a5d820c34..e2ca8ddc8ebebf4e 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -1685,6 +1685,11 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) > if (!size) > return; > > + if (memblock.memory.cnt <= 1) { > + pr_warn("%s: No memory registered yet\n", __func__); > + return; > + } > + > ret = memblock_isolate_range(&memblock.memory, base, size, > &start_rgn, &end_rgn); > if (ret) > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb