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[24.233.113.151]) by smtp.gmail.com with ESMTPSA id e19-20020ad44433000000b006848cc2817esm275036qvt.33.2024.02.08.15.50.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Feb 2024 15:50:15 -0800 (PST) Message-ID: <90cbea27-8752-403f-9e0d-3aaa19100923@google.com> Date: Thu, 8 Feb 2024 18:50:14 -0500 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next 04/16] bpf: Introduce bpf_arena. Content-Language: en-US To: Alexei Starovoitov Cc: bpf , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Eddy Z , Tejun Heo , Johannes Weiner , linux-mm , Kernel Team References: <20240206220441.38311-1-alexei.starovoitov@gmail.com> <20240206220441.38311-5-alexei.starovoitov@gmail.com> From: Barret Rhoden In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/8/24 18:36, Alexei Starovoitov wrote: > I'm inclined to tackle wrap32 issue differently and simply > disallow [user_vm_start, user_vm_end] combination > where lower 32-bit can wrap. > > In other words it would mean that mmap() of len=4Gb will be > aligned to 4Gb, > while mmap() of len=1M will be offsetted in such a way > that both addr and add+1M have the same upper 32-bit. > (It's not the same as 1M aligned). > > With that I will remove vmap_pages_range_wrap32() and > do single normal vmap_pages_range() without extra tricks. > > wdyt? SGTM. knowing that you can't wrap the lower 32 removes a lot of headaches. and the restriction of aligning a 4GB mapping to 4GB boundary is pretty sane. TBH doing it elsewhere is just asking for heartache. =) barret