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From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Enke Chen <enkechen@cisco.com>, Dave Martin <Dave.Martin@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	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>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <christian@brauner.io>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Will Deacon <Will.Deacon@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>,
	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-kernel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"Victor Kamensky (kamensky)" <kamensky@cisco.com>,
	"xe-linux-external@cisco.com" <xe-linux-external@cisco.com>,
	Stefan Strogin <sstrogin@cisco.com>
Subject: Re: [PATCH v5 1/2] kernel/signal: Signal-based pre-coredump notification
Date: Thu, 6 Dec 2018 18:29:32 +0100	[thread overview]
Message-ID: <20181206172931.GA12967@redhat.com> (raw)
In-Reply-To: <20181204143759.fe24ee036a33000193339561@linux-foundation.org>

On 12/04, Andrew Morton wrote:
>
> I'm not sure what to make of this patchset, really.  Oleg sounds
> unhappy and that's always a bad sign.  And signals are rather ugly
> things.  Oleg, can you please expand on your concerns?

I don't really know what can I say...

Yes the signals are ugly things, this is one reason. Worse, you need to
use real-time predump_signal if parent has 2 or more children.

And when it comes to child-parent notifications we already have do_wait().
So probably it would be better to implement WCOREDUMP so that the parent
could rely on SIGCHLD + waitpid(WCOREDUMP). Not that I think this is a
good idea and this is much more complex especially if we want to report
this event to ptracer too, while this patch is very simple.

In fact I think that we need something more generic, but I can't suggest
any good idea :/

May be we could simply add a tracepoint or perf_event_coredump, I dunno.
Sure, the usage of perf events is not that simple...

Oleg.


  reply	other threads:[~2018-12-06 17:29 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
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 [this message]
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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