From: Enke Chen <enkechen@cisco.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Arnd Bergmann <arnd@arndb.de>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Khalid Aziz <khalid.aziz@oracle.com>,
Kate Stewart <kstewart@linuxfoundation.org>,
Helge Deller <deller@gmx.de>, Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian@brauner.io>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Dave Martin <Dave.Martin@arm.com>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
Michal Hocko <mhocko@kernel.org>, Rik van Riel <riel@surriel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Roman Gushchin <guro@fb.com>,
Marcos Paulo de Souza <marcos.souza.org@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Yang Shi <yang.shi@linux.alibaba.com>,
Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
"Victor Kamensky (kamensky)" <kamensky@cisco.com>,
xe-linux-external@cisco.com, Stefan Strogin <sstrogin@cisco.com>,
Enke Chen <enkechen@cisco.com>
Subject: Re: [PATCH] kernel/signal: Signal-based pre-coredump notification
Date: Mon, 15 Oct 2018 11:16:36 -0700 [thread overview]
Message-ID: <37401cea-5a37-2cd9-8595-8b07dfc4de7d@cisco.com> (raw)
In-Reply-To: <20181013064023.GA28177@kroah.com>
Hi, Greg:
> Shouldn't there also be a manpage update, and a kselftest added for this
> new user/kernel api that is being created?
>
I will submit a patch for manpage update once the code is accepted.
Regarding the kselftest, I am not sure. Once the prctl() is limited to
self (which I will do), the logic would be pretty straightforward. Not
sure if the selftest would add much value.
Thanks. -- Enke
On 10/12/18 11:40 PM, Greg Kroah-Hartman wrote:
> On Fri, Oct 12, 2018 at 05:33:35PM -0700, Enke Chen wrote:
>> For simplicity and consistency, this patch provides an implementation
>> for signal-based fault notification prior to the coredump of a child
>> process. A new prctl command, PR_SET_PREDUMP_SIG, is defined that can
>> be used by an application to express its interest and to specify the
>> signal (SIGCHLD or SIGUSR1 or SIGUSR2) for such a notification. A new
>> signal code (si_code), CLD_PREDUMP, is also defined for SIGCHLD.
>>
>> Background:
>>
>> As the coredump of a process may take time, in certain time-sensitive
>> applications it is necessary for a parent process (e.g., a process
>> manager) to be notified of a child's imminent death before the coredump
>> so that the parent process can act sooner, such as re-spawning an
>> application process, or initiating a control-plane fail-over.
>>
>> Currently there are two ways for a parent process to be notified of a
>> child process's state change. One is to use the POSIX signal, and
>> another is to use the kernel connector module. The specific events and
>> actions are summarized as follows:
>>
>> Process Event POSIX Signal Connector-based
>> ----------------------------------------------------------------------
>> ptrace_attach() do_notify_parent_cldstop() proc_ptrace_connector()
>> SIGCHLD / CLD_STOPPED
>>
>> ptrace_detach() do_notify_parent_cldstop() proc_ptrace_connector()
>> SIGCHLD / CLD_CONTINUED
>>
>> pre_coredump/ N/A proc_coredump_connector()
>> get_signal()
>>
>> post_coredump/ do_notify_parent() proc_exit_connector()
>> do_exit() SIGCHLD / exit_signal
>> ----------------------------------------------------------------------
>>
>> As shown in the table, the signal-based pre-coredump notification is not
>> currently available. In some cases using a connector-based notification
>> can be quite complicated (e.g., when a process manager is written in shell
>> scripts and thus is subject to certain inherent limitations), and a
>> signal-based notification would be simpler and better suited.
>>
>> Signed-off-by: Enke Chen <enkechen@cisco.com>
>> ---
>> arch/x86/kernel/signal_compat.c | 2 +-
>> include/linux/sched.h | 4 ++
>> include/linux/signal.h | 5 +++
>> include/uapi/asm-generic/siginfo.h | 3 +-
>> include/uapi/linux/prctl.h | 4 ++
>> kernel/fork.c | 1 +
>> kernel/signal.c | 51 +++++++++++++++++++++++++
>> kernel/sys.c | 77 ++++++++++++++++++++++++++++++++++++++
>> 8 files changed, 145 insertions(+), 2 deletions(-)
>
> Shouldn't there also be a manpage update, and a kselftest added for this
> new user/kernel api that is being created?
>
> thanks,
>
> greg k-h
>
next prev parent reply other threads:[~2018-10-15 18:16 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-13 0:33 [PATCH] kernel/signal: Signal-based pre-coredump notification Enke Chen
2018-10-13 6:40 ` Greg Kroah-Hartman
2018-10-15 18:16 ` Enke Chen [this message]
2018-10-15 18:43 ` Greg Kroah-Hartman
2018-10-15 18:49 ` Enke Chen
2018-10-15 18:58 ` Greg Kroah-Hartman
2018-10-13 10:44 ` Christian Brauner
2018-10-15 18:39 ` Enke Chen
2018-10-13 18:27 ` Jann Horn
2018-10-15 18:36 ` Enke Chen
2018-10-15 18:54 ` Jann Horn
2018-10-15 19:23 ` Enke Chen
2018-10-19 23:01 ` Enke Chen
2018-10-22 15:40 ` Jann Horn
2018-10-22 20:48 ` Enke Chen
2018-10-15 12:05 ` Oleg Nesterov
2018-10-15 18:54 ` Enke Chen
2018-10-15 19:17 ` Enke Chen
2018-10-15 19:26 ` Enke Chen
2018-10-16 14:14 ` Oleg Nesterov
2018-10-16 15:09 ` Eric W. Biederman
2018-10-17 0:39 ` Enke Chen
2018-10-15 21:21 ` Alan Cox
2018-10-15 21:31 ` Enke Chen
2018-10-15 23:28 ` Eric W. Biederman
2018-10-16 0:33 ` valdis.kletnieks
2018-10-16 0:54 ` Enke Chen
2018-10-16 15:26 ` Eric W. Biederman
2018-10-22 21:09 ` [PATCH v2] " Enke Chen
2018-10-23 9:23 ` Oleg Nesterov
2018-10-23 19:43 ` Enke Chen
2018-10-23 21:40 ` Enke Chen
2018-10-24 13:52 ` Oleg Nesterov
2018-10-24 21:56 ` Enke Chen
2018-10-24 5:39 ` [PATCH v3] " Enke Chen
2018-10-24 14:02 ` Oleg Nesterov
2018-10-24 22:02 ` Enke Chen
2018-10-25 22:56 ` [PATCH v4] " Enke Chen
2018-10-26 8:28 ` Oleg Nesterov
2018-10-26 22:23 ` Enke Chen
2018-10-29 11:18 ` Oleg Nesterov
2018-10-29 21:08 ` Enke Chen
2018-10-29 22:31 ` [PATCH v5] " Enke Chen
2018-10-30 16:46 ` Oleg Nesterov
2018-10-31 0:25 ` Enke Chen
2018-11-22 0:37 ` Andrew Morton
2018-11-22 1:09 ` Enke Chen
2018-11-22 1:18 ` Enke Chen
2018-11-22 1:33 ` Andrew Morton
2018-11-22 4:57 ` Enke Chen
2018-11-12 23:22 ` Enke Chen
2018-11-27 22:54 ` [PATCH v5 1/2] " Enke Chen
2018-11-28 15:19 ` Dave Martin
2018-11-29 0:15 ` Enke Chen
2018-11-29 11:55 ` Dave Martin
2018-11-30 0:27 ` Enke Chen
2018-11-30 12:03 ` Oleg Nesterov
2018-12-05 6:47 ` Jann Horn
2018-12-04 22:37 ` Andrew Morton
2018-12-06 17:29 ` Oleg Nesterov
2018-10-25 22:56 ` [PATCH] selftests/prctl: selftest for pre-coredump signal notification Enke Chen
2018-11-27 22:54 ` [PATCH v5 2/2] " Enke Chen
2018-10-24 13:29 ` [PATCH v2] kernel/signal: Signal-based pre-coredump notification Eric W. Biederman
2018-10-24 23:50 ` Enke Chen
2018-10-25 12:23 ` Eric W. Biederman
2018-10-25 20:45 ` Enke Chen
2018-10-25 21:24 ` Enke Chen
2018-10-25 21:56 ` Enke Chen
2018-10-25 13:45 ` Jann Horn
2018-10-25 20:21 ` Eric W. Biederman
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