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AJvYcCX4wDEUFDUi7Bef1T9i2RUQg4uIGS1ICqlPkSxuyBydVqyn+YBs8247vdXx2MjgF5zMbZ9h5EwxQQ==@kvack.org X-Gm-Message-State: AOJu0Ywlh5jyLeMTtXd2qexM38KiVwgOhE2wXVdLGd74WsFV3/5omVj6 jk3+2hTLS+FCRksYHir8J1Hgssg8cGu6+56s5J7PAsnnnnaz1NbxcQ3/GLgiuCa0mkV5QgiV+sr Gp6k3YyAk5oB018a3artsTFBwP8tglw4S0Twa X-Gm-Gg: ASbGnctTS6XaUVRtmxZJMwNTF+qZP7mDN2MzCgOZ60iYSrAWY25EkYwIlkaFf5aNUUB ODcSMWjgo9bVrcQti32A2NZEuuaBKUutn6m62gu6WI22iJsFQ0HuZII1ou3w= X-Google-Smtp-Source: AGHT+IEua20Eqb1JaSJTjoS41LVjYaqL8FMfX/x58myfzkw5AxRCOo+g07QT8Vi+Hj5kojc7NvaYaZVtD/vPKtNbGpo= X-Received: by 2002:aa7:c913:0:b0:5d0:b20c:205c with SMTP id 4fb4d7f45d1cf-5d0b20c22abmr52383a12.5.1732904038464; Fri, 29 Nov 2024 10:13:58 -0800 (PST) MIME-Version: 1.0 References: <20241129155943.85215-1-lorenzo.stoakes@oracle.com> In-Reply-To: <20241129155943.85215-1-lorenzo.stoakes@oracle.com> From: Jann Horn Date: Fri, 29 Nov 2024 19:13:22 +0100 Message-ID: Subject: Re: [PATCH man-pages v2] madvise.2: add MADV_GUARD_INSTALL, MADV_GUARD_REMOVE description To: Lorenzo Stoakes Cc: Alejandro Colomar , linux-man@vger.kernel.org, Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , Vlastimil Babka , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9DF681C000B X-Stat-Signature: cfdg75sgrttxdhotx9y1md8j3sn4qb8n X-HE-Tag: 1732904036-276274 X-HE-Meta: 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 QPcVFgCH 4oscwQk5VOPvxAejtiapYZc3dEZZR3fKjrjisOYVWr/ftvRKMC3GL+0bt1usIdOU38XC6zCYmmhcQlX55vNEpf/U7MZWzMRvm8JbmwDUalGRfYRwwmOwORwk+ltwtF9Z/rCfV9rGLI9+4PrYV4MzKul0oWRmL9GHBdRcunZwGE0X1mAO6/8XB5jrFB7JKvBHbLYjCiuOpeNKJUEkVSrFaVBGXU5yBU0zqdTCW/h3P+vOVXnalslyb1ybWhh7Joq9b6XueAkWj6m7P60Y= X-Bogosity: Ham, tests=bogofilter, spamicity=0.021675, 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 Fri, Nov 29, 2024 at 4:59=E2=80=AFPM Lorenzo Stoakes wrote: > Lightweight guard region support has been added to Linux 6.13, which adds > MADV_GUARD_INSTALL and MADV_GUARD_REMOVE flags to the madvise() system > call. Therefore, update the manpage for madvise() and describe these > operations. [...] > +.TP > +.BR MADV_GUARD_INSTALL " (since Linux 6.13)" > +Install a lightweight guard region into the range specified by > +.I addr > +and > +.IR size , > +causing any read or write in the range to result in a fatal > +.B SIGSEGV > +signal being raised. Single-word nitpick: Maybe remove the word "fatal"? I think the term "fatal signal" normally refers to a signal that is guaranteed to terminate the task (that's how the signal handling code uses the term, more or less); but a SIGSEGV caused by VM_FAULT_SIGSEGV can AFAIK be handled by a userspace signal handler. SIGKILL is the one signal that is always fatal; the kernel can also send other signals in an always-fatal way, like with force_fatal_sig() or force_exit_sig(), but those are not used for VM_FAULT_SIGSEGV. (Those functions are mostly for cases where we can't continue because something is in an unsafe state, like if a signal return failed and the register state might now be messed up.)