From: Pavel Machek <pavel@ucw.cz>
To: Miroslav Benes <mbenes@suse.cz>
Cc: jpoimboe@redhat.com, jeyu@kernel.org, jikos@kernel.org,
pmladek@suse.com, lpechacek@suse.cz,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] livepatch: force transition process to finish
Date: Mon, 6 Nov 2017 12:11:05 +0100 [thread overview]
Message-ID: <20171106111105.GC24863@amd> (raw)
In-Reply-To: <20171031114853.841-3-mbenes@suse.cz>
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On Tue 2017-10-31 12:48:53, Miroslav Benes wrote:
> If a task sleeps in a set of patched functions uninterruptedly, it could
> block the whole transition process indefinitely. Thus it may be useful
> to clear its TIF_PATCH_PENDING to allow the process to finish.
>
> Admin can do that now by writing to force sysfs attribute in livepatch
> sysfs directory. TIF_PATCH_PENDING is then cleared for all tasks and the
> transition can finish successfully.
>
> Important note! Use wisely. Admin must be sure that it is safe to
> execute such action. This means that it must be checked that by doing so
> the consistency model guarantees are not violated.
>
> Signed-off-by: Miroslav Benes <mbenes@suse.cz>
> ---
> Documentation/ABI/testing/sysfs-kernel-livepatch | 10 +++++++++
> Documentation/livepatch/livepatch.txt | 24 +++++++++++++++------
> kernel/livepatch/core.c | 27 ++++++++++++++++++++++++
> kernel/livepatch/transition.c | 25 ++++++++++++++++++++++
> kernel/livepatch/transition.h | 1 +
> 5 files changed, 81 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
> index 22f6267836c2..105f617008f1 100644
> --- a/Documentation/ABI/testing/sysfs-kernel-livepatch
> +++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
> @@ -42,6 +42,16 @@ Contact: live-patching@vger.kernel.org
> course of an existing transition. Writing 1 sends a signal to
> all remaining blocking tasks.
>
> +What: /sys/kernel/livepatch/<patch>/force
> +Date: Oct 2017
> +KernelVersion: 4.15.0
> +Contact: live-patching@vger.kernel.org
> +Description:
> + A writable attribute that allows administrator to affect the
> + course of an existing transition. Writing 1 clears
> + TIF_PATCH_PENDING flag of all tasks and thus forces the tasks to
> + the patched or unpatched state.
> +
NAK. Admin does not have chance to decide if this is safe or not.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2017-11-06 11:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 11:48 [PATCH v3 0/2] livepatch: Introduce signal and force sysfs attributes Miroslav Benes
2017-10-31 11:48 ` [PATCH v3 1/2] livepatch: send a fake signal to all blocking tasks Miroslav Benes
2017-11-01 15:06 ` Miroslav Benes
2017-11-01 15:13 ` Petr Mladek
2017-11-01 16:43 ` Oleg Nesterov
2017-11-02 10:36 ` Miroslav Benes
2017-11-02 14:08 ` Oleg Nesterov
2017-11-02 13:09 ` Josh Poimboeuf
2017-11-03 8:02 ` Miroslav Benes
2017-11-03 12:57 ` Josh Poimboeuf
2017-11-02 13:32 ` Josh Poimboeuf
2017-11-03 8:06 ` Miroslav Benes
2017-11-06 11:08 ` Pavel Machek
2017-10-31 11:48 ` [PATCH v3 2/2] livepatch: force transition process to finish Miroslav Benes
2017-11-01 15:32 ` Petr Mladek
2017-11-02 13:13 ` Josh Poimboeuf
2017-11-03 8:07 ` Miroslav Benes
2017-11-06 11:11 ` Pavel Machek [this message]
2017-11-06 12:03 ` Jiri Kosina
2017-11-09 11:14 ` Pavel Machek
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