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[209.85.218.49]) by smtp.gmail.com with ESMTPSA id y14-20020a056402440e00b00416046b623csm9713676eda.2.2022.04.19.19.26.39 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Apr 2022 19:26:39 -0700 (PDT) Received: by mail-ej1-f49.google.com with SMTP id l7so690702ejn.2 for ; Tue, 19 Apr 2022 19:26:39 -0700 (PDT) X-Received: by 2002:a2e:9041:0:b0:24a:ce83:dcb4 with SMTP id n1-20020a2e9041000000b0024ace83dcb4mr12387816ljg.291.1650421146776; Tue, 19 Apr 2022 19:19:06 -0700 (PDT) MIME-Version: 1.0 References: <4AD023F9-FBCE-4C7C-A049-9292491408AA@fb.com> <88eafc9220d134d72db9eb381114432e71903022.camel@intel.com> <20220420020311.6ojfhcooumflnbbk@MacBook-Pro.local.dhcp.thefacebook.com> In-Reply-To: <20220420020311.6ojfhcooumflnbbk@MacBook-Pro.local.dhcp.thefacebook.com> From: Linus Torvalds Date: Tue, 19 Apr 2022 19:18:50 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP To: Alexei Starovoitov Cc: Mike Rapoport , Song Liu , "Edgecombe, Rick P" , "mcgrof@kernel.org" , "linux-kernel@vger.kernel.org" , "bpf@vger.kernel.org" , "hch@infradead.org" , "ast@kernel.org" , "daniel@iogearbox.net" , "linux-mm@kvack.org" , "song@kernel.org" , Kernel Team , "pmladek@suse.com" , "akpm@linux-foundation.org" , "hpa@zytor.com" , "dborkman@redhat.com" , "edumazet@google.com" , "bp@alien8.de" , "mbenes@suse.cz" , "imbrenda@linux.ibm.com" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B98CF140011 X-Rspam-User: Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=XlMHlA1y; spf=pass (imf23.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.50 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none X-Stat-Signature: x5wo9fhrdkfwuw6cibdtozpox5bhkhru X-HE-Tag: 1650421599-865726 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 Tue, Apr 19, 2022 at 7:03 PM Alexei Starovoitov wrote: > > Here is the quote from Song's cover letter for bpf_prog_pack series: I care about performance as much as the next person, but I care about correctness too. That large-page code was a disaster, and was buggy and broken. And even with those four patches, it's still broken. End result: there's no way that thigh gets re-enabled without the correctness being in place. At a minimum, to re-enable it, it needs (a) that zeroing and (b) actual numbers on real loads. (not some artificial benchmark). Because without (a) there's no way in hell I'll enable it. And without (b), "performance" isn't actually an argument. Linus