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Thu, 21 Nov 2024 09:33:58 -0500 (EST) Date: Thu, 21 Nov 2024 07:33:54 -0700 From: Tycho Andersen To: Christian Brauner Cc: Yun Zhou , stgraber@stgraber.org, cyphar@cyphar.com, Alexander Mikhalitsyn , mcgrof@kernel.org, kees@kernel.org, joel.granados@kernel.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v2] kernel: add pid_max to pid_namespace Message-ID: References: <20241105031024.3866383-1-yun.zhou@windriver.com> <20241120-entgiften-geldhahn-a9d2922ec3e0@brauner> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241120-entgiften-geldhahn-a9d2922ec3e0@brauner> On Wed, Nov 20, 2024 at 10:06:27AM +0100, Christian Brauner wrote: > On Tue, Nov 05, 2024 at 11:10:24AM +0800, Yun Zhou wrote: > > It is necessary to have a different pid_max in different containers. > > For example, multiple containers are running on a host, one of which > > is Android, and its 32 bit bionic libc only accepts pid <= 65535. So > > it requires the global pid_max <= 65535. This will cause configuration > > conflicts with other containers and also limit the maximum number of > > tasks for the entire system. > > > > Signed-off-by: Yun Zhou > > --- > > Fwiw, I've done a patch like this years ago and then Alex revived it in > [1] including selftests! There's downsides to consider: > > [1]: https://lore.kernel.org/lkml/20240222160915.315255-1-aleksandr.mikhalitsyn@canonical.com Thanks, looks like this patch has the same oddity. For me it's enough to just walk up the tree when changing pid_max. It seems unlikely that applications will create a sub pidns and then lower the max in their own pid_max. Famous last words and all that. Tycho