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AJvYcCUOZ1xILMFApSiwsriImwm75gOnu+/B+4kXNSMu15fGzFtMQUxgi0yulw1OrQ6bCc9z/UBeG1ArfAr0lS8axRzYtjw= X-Gm-Message-State: AOJu0Yz9M4eqExodTj0jkdCQugypsD3bELKmAIKBwm7Z5ubtzxlMv4S8 H4wMtyaAKbEJZE4XFh9LLcT3Ax5Imk+p54ux5lzn1Oy8xiC9ch6QwY5IID3hT6P0FK3Xs8Pm0h1 MMTdCFWMgzpuG5MLePcpb4wkycwfzTHxYGsUw X-Google-Smtp-Source: AGHT+IGqv2dvKxmgA37AXYwXcqcy+VUarFEug/q6Qajf1/shsAVDJ2FVpYt5LV0ZKu34PjuRvF0l1baRqWG8DdWGDA4= X-Received: by 2002:a05:690c:f94:b0:63b:d711:e722 with SMTP id 00721157ae682-6b1b9b5ac7cmr168081857b3.1.1724120529883; Mon, 19 Aug 2024 19:22:09 -0700 (PDT) MIME-Version: 1.0 References: <20240819151512.2363698-1-surenb@google.com> <20240819151512.2363698-6-surenb@google.com> <20240819184649.8fc7da59f89290f716ae0553@linux-foundation.org> In-Reply-To: <20240819184649.8fc7da59f89290f716ae0553@linux-foundation.org> From: Suren Baghdasaryan Date: Mon, 19 Aug 2024 19:21:57 -0700 Message-ID: Subject: Re: [PATCH 5/5] alloc_tag: config to store page allocation tag refs in page flags To: Andrew Morton Cc: Matthew Wilcox , kent.overstreet@linux.dev, corbet@lwn.net, arnd@arndb.de, mcgrof@kernel.org, rppt@kernel.org, paulmck@kernel.org, thuth@redhat.com, tglx@linutronix.de, bp@alien8.de, xiongwei.song@windriver.com, ardb@kernel.org, david@redhat.com, vbabka@suse.cz, mhocko@suse.com, hannes@cmpxchg.org, roman.gushchin@linux.dev, dave@stgolabs.net, liam.howlett@oracle.com, pasha.tatashin@soleen.com, souravpanda@google.com, keescook@chromium.org, dennis@kernel.org, jhubbard@nvidia.com, yuzhao@google.com, vvvvvv@google.com, rostedt@goodmis.org, iamjoonsoo.kim@lge.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 509F6140015 X-Stat-Signature: sf546q1qfw3imj7e3en56egskryxa8qe X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1724120531-235627 X-HE-Meta: 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 LQGi1bW/ WRVx8lUR4XUUjJvtjeSl3dFD3/CP7V9aODtvKiUrlk1SufomxmY9zZ4z2bRVSzgYBPo8HP5Q+I+9lC6w1fjgUXmf7v9z/H6/DoVswcc5Axdsdr+7FQpUl9HOiaGH13pVjt+0ur/4F+msbxEMHmjljrPgo0bJcOFnxV0kYd/z1V54egWBBxh4fe2SyJS0AqhfMwRUh7o3cKi9+OBmsJnFuuqO0l5rJdSc1x5mCbDPilesKSXRwqeYHhruzZFmI2gYY5zsLCxNU5CpztArcZTt3cNUrEaqKaZzMyWD6RYty3a0lpNBF2iRCVInXz70u9rxgsFJ+Xi7JGjM/JnQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000096, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 19, 2024 at 6:46=E2=80=AFPM Andrew Morton wrote: > > On Mon, 19 Aug 2024 21:40:34 +0100 Matthew Wilcox w= rote: > > > On Mon, Aug 19, 2024 at 01:39:16PM -0700, Suren Baghdasaryan wrote: > > > On Mon, Aug 19, 2024 at 12:34=E2=80=AFPM Matthew Wilcox wrote: > > > > So if ALLOC_TAG_REF_WIDTH is big enough, it's going to force last_c= pupid > > > > into struct page. > > > > > > Thanks for taking a look! > > > Yes, but how is this field different from say KASAN_TAG_WIDTH which > > > can also force last_cpupid out of page flags? > > > > Because KASAN isn't for production use? > > > > > > That will misalign struct page and disable HVO -- with no warning! > > > > > > mminit_verify_pageflags_layout already has a mminit_dprintk() to > > > indicate this condition. Is that not enough? > > > > Fair. > > Is a BUILD_BUG_ON() feasible here? We could, but I didn't think we should prevent people from having such a configuration if that's what they need...