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[209.85.218.54]) by smtp.gmail.com with ESMTPSA id q2-20020a056402032200b00423d4516387sm8192913edw.75.2022.04.21.09.21.05 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Apr 2022 09:21:05 -0700 (PDT) Received: by mail-ej1-f54.google.com with SMTP id r13so11102167ejd.5 for ; Thu, 21 Apr 2022 09:21:05 -0700 (PDT) X-Received: by 2002:a05:6512:6d4:b0:470:f48d:44e2 with SMTP id u20-20020a05651206d400b00470f48d44e2mr173410lff.542.1650557721884; Thu, 21 Apr 2022 09:15:21 -0700 (PDT) MIME-Version: 1.0 References: <20220415164413.2727220-1-song@kernel.org> <4AD023F9-FBCE-4C7C-A049-9292491408AA@fb.com> <88eafc9220d134d72db9eb381114432e71903022.camel@intel.com> <1650511496.iys9nxdueb.astroid@bobo.none> <1650530694.evuxjgtju7.astroid@bobo.none> <25437eade8b2ecf52ff9666a7de9e36928b7d28f.camel@intel.com> In-Reply-To: <25437eade8b2ecf52ff9666a7de9e36928b7d28f.camel@intel.com> From: Linus Torvalds Date: Thu, 21 Apr 2022 09:15:05 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP To: "Edgecombe, Rick P" Cc: "npiggin@gmail.com" , "songliubraving@fb.com" , "linux-kernel@vger.kernel.org" , "daniel@iogearbox.net" , "bpf@vger.kernel.org" , "hch@infradead.org" , "ast@kernel.org" , "Kernel-team@fb.com" , "linux-mm@kvack.org" , "rppt@kernel.org" , "song@kernel.org" , "pmladek@suse.com" , "akpm@linux-foundation.org" , "hpa@zytor.com" , "dborkman@redhat.com" , "edumazet@google.com" , "bp@alien8.de" , "mcgrof@kernel.org" , "mbenes@suse.cz" , "imbrenda@linux.ibm.com" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 466AE100030 X-Stat-Signature: 8zftwjge9xqumcfxrf5rzkwqwgb936w4 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=DIriM5i3; spf=pass (imf05.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none X-Rspam-User: X-HE-Tag: 1650558065-499012 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 Thu, Apr 21, 2022 at 8:47 AM Edgecombe, Rick P wrote: > > I wonder if it > might have to do with the vmalloc huge pages using compound pages, then > some caller doing vmalloc_to_page() and getting surprised with what > they could get away with in the struct page. Very likely. We have 100+ users of vmalloc_to_page() in random drivers, and the gpu code does show up on that list. And is very much another case of "it's always been broken, but enabling it on x86 made the breakage actually show up in real life". Linus