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Fri, 23 Oct 2026 05:16:27 -0700 (PDT) Received: from [192.168.2.110] ([142.172.30.162]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-536c18b0e2asm14855791cf.28.2026.10.23.05.16.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 Oct 2026 05:16:27 -0700 (PDT) Message-ID: <50545ab3-bf06-456d-8d14-2536f90f6f65@redhat.com> Date: Fri, 23 Oct 2026 08:16:26 -0400 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] mremap() fails VMA expansion when VM_MIXEDMAP is set To: "Lorenzo Stoakes (ARM)" , "Vlastimil Babka (SUSE)" Cc: Andrew Morton , "Liam R. Howlett" , Jann Horn , Pedro Falcato , David Hildenbrand , Jakub Matena , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20261023023106.515365-1-luizcap@redhat.com> <8c53e58c-f7d2-4e98-8d03-7ff1163c1159@kernel.org> Content-Language: en-US From: Luiz Capitulino In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/23/26 4:19 AM, Lorenzo Stoakes (ARM) wrote: > On Fri, Oct 23, 2026 at 09:16:12AM +0200, Vlastimil Babka (SUSE) wrote: >> On 10/23/26 04:31, Luiz Capitulino wrote: > >>> This regression was introduced in v6.1 by commit ca3d76b0aa80 ("mm: add merging >>> after mremap resize"). This commit changed mremap() to use vma_merge() instead >>> of vma_adjust() for the expansion case. However, vma_merge() returns NULL for >>> a VMA that has any of the VM_SPECIAL flags set. >> >> Hi, >> >> 6.1 was a rather long time ago. How was it discovered just now? I.e. what >> use case broke by the change and prompted creating the reproducer? >> >> Vlastimil >> Thanks, > > Thanks, I have the same questions :) > > Do always include that kind of information and whether it was an LLM-discovered > thing or whether you had an actual workload that was impacted, etc. Will do the next time, I claried the use-case in my response to Vlastimil. > > -- > Cheers, Lorenzo