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Tue, 04 Feb 2025 09:43:43 -0800 (PST) MIME-Version: 1.0 References: <20250204-joggen-buddeln-29e5ca75abb7@brauner> <7a8a1719-466f-4e10-b1eb-9e9e1ef8ad52@lucifer.local> In-Reply-To: <7a8a1719-466f-4e10-b1eb-9e9e1ef8ad52@lucifer.local> From: Suren Baghdasaryan Date: Tue, 4 Feb 2025 09:43:31 -0800 X-Gm-Features: AWEUYZl7RlmyhEU99QQ-tyghSf0sZ-KKDjjpT9EgshNSpko_7zG64QXhfE_k9kk Message-ID: Subject: Re: [PATCH v7 0/6] introduce PIDFD_SELF* sentinels To: Lorenzo Stoakes Cc: Christian Brauner , Shuah Khan , "Liam R . Howlett" , Vlastimil Babka , pedro.falcato@gmail.com, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Oliver Sang , John Hubbard , Tejun Heo , Johannes Weiner , Michal Koutny , Andrew Morton , Shakeel Butt , Elliott Hughes Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B05BF180012 X-Stat-Signature: c8fnewyogkjpniekcp45obcresi9ban7 X-HE-Tag: 1738691024-846864 X-HE-Meta: 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 KUiWoC+w Prn7NKbobROcBELVjbJGOO1XitKALRLVU7mVj91AfNFFPEfaGAsAqZMXglff4+aOBMpsYcKDDD5yq9tcThxQtfxSqGDxu84IfDjY/xi840kmOFsHltlUpBF/CFxw0PBp+pheRN2/I7LIYNYbVYSh2bvz67i0w1PrYhObZZEAr3I22NqNoAUQU/SePMjRmzYymLQhc6RIO6XM15i7OJZKQMkLcBcMZ6HeuBjsndxca1eFGLz7BkAekahyJXx67BPqFjWJi/498yHKinOVjmmPuzF9LZSHc+tvEer5VhHTHjCd0TFMUqKQr6QYT+yODSOuZg41K1PBx2nMo6PYuog7c0OJwt/oaat+WrafiN/7ZmhpZ8k4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000543, 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 Tue, Feb 4, 2025 at 2:01=E2=80=AFAM Lorenzo Stoakes wrote: > > On Tue, Feb 04, 2025 at 10:46:35AM +0100, Christian Brauner wrote: > > On Thu, 30 Jan 2025 20:40:25 +0000, Lorenzo Stoakes wrote: > > > If you wish to utilise a pidfd interface to refer to the current proc= ess or > > > thread it is rather cumbersome, requiring something like: > > > > > > int pidfd =3D pidfd_open(getpid(), 0 or PIDFD_THREAD); > > > > > > ... > > > > > > [...] > > > > Updated merge message. I've slightly rearranged pidfd_send_signal() so > > we don't have to call CLASS(fd, f)(pidfd) unconditionally anymore. > > Sounds good and thank you! Glad to get this in :) Sorry, a bit late to the party... We were discussing MADV_GUARD_INSTALL use with Android Bionic team and the possibility of caching pidfd_open() result for reuse when installing multiple guards, however doing that in libraries would pose issues as we can't predict the user behavior, which can fork() in between such calls. That would be an additional reason why having these sentinels is beneficial. > > > > > --- > > > > Applied to the vfs-6.15.pidfs branch of the vfs/vfs.git tree. > > Patches in the vfs-6.15.pidfs branch should appear in linux-next soon. > > > > Please report any outstanding bugs that were missed during review in a > > new review to the original patch series allowing us to drop it. > > > > It's encouraged to provide Acked-bys and Reviewed-bys even though the > > patch has now been applied. If possible patch trailers will be updated. > > > > Note that commit hashes shown below are subject to change due to rebase= , > > trailer updates or similar. If in doubt, please check the listed branch= . > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git > > branch: vfs-6.15.pidfs > > > > [1/6] pidfd: add PIDFD_SELF* sentinels to refer to own thread/process > > https://git.kernel.org/vfs/vfs/c/e6e4ed42f8d8 > > [2/6] selftests/pidfd: add missing system header imcludes to pidfd test= s > > https://git.kernel.org/vfs/vfs/c/c9f04f4a251d > > [3/6] tools: testing: separate out wait_for_pid() into helper header > > https://git.kernel.org/vfs/vfs/c/fb67fe44116e > > [4/6] selftests: pidfd: add pidfd.h UAPI wrapper > > https://git.kernel.org/vfs/vfs/c/ac331e56724d > > [5/6] selftests: pidfd: add tests for PIDFD_SELF_* > > https://git.kernel.org/vfs/vfs/c/881a3515c191 > > [6/6] selftests/mm: use PIDFD_SELF in guard pages test > > https://git.kernel.org/vfs/vfs/c/b4703f056f42