From: Vojtech Pavlik <vojtech@suse.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>, Jiri Kosina <jikos@kernel.org>,
Jessica Yu <jeyu@redhat.com>,
linux-kernel@vger.kernel.org, live-patching@vger.kernel.org
Subject: Re: [RFC PATCH v1.9 12/14] livepatch: create per-task consistency model
Date: Mon, 4 Apr 2016 20:27:59 +0200 [thread overview]
Message-ID: <20160404182759.GA10777@suse.cz> (raw)
In-Reply-To: <20160404182138.pjze2fvtmknq2ksq@treble.redhat.com>
On Mon, Apr 04, 2016 at 01:21:38PM -0500, Josh Poimboeuf wrote:
> Hm, can you explain why it should be copied from the parent?
>
> I'm thinking the above code is correct for today, but it should still be
> changed to be more future-proof.
>
> Here's my thinking:
>
> A forked task starts out with no stack, so if I understand correctly, it
> can safely start out in the goal universe, regardless of which universe
> its parent belongs to.
>
> However, the current ret_from_fork code is a mess, and Andy Lutomirski
> has mentioned that he would like to give newly forked tasks a proper
> stack such that instead of jumping to ret_from_fork, they would just
> return from schedule(). In that case, it would no longer be safe to
> start the new task in the goal universe because it could be "sleeping"
> on a to-be-patched function.
>
> So for proper future proofing, newly forked tasks should be started in
> the initial universe (rather than starting in the goal universe or
> inheriting the parent's universe). They can then be transitioned over
> to the goal universe like any other task. How does that sound?
How could a newly forked task start in the old universe if its parent
has already been migrated? Any context it inherits will already be from
the new universe.
--
Vojtech Pavlik
Director SuSE Labs
next prev parent reply other threads:[~2016-04-04 19:00 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-25 19:34 [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 01/14] x86/asm/head: cleanup initial stack variable Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 02/14] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 03/14] x86/asm/head: standardize the bottom of the stack for idle tasks Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 04/14] x86: move _stext marker before head code Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a task has been preempted Josh Poimboeuf
2016-04-06 13:06 ` Petr Mladek
2016-04-06 16:33 ` Josh Poimboeuf
2016-04-07 9:47 ` Petr Mladek
2016-04-07 14:34 ` Josh Poimboeuf
2016-04-08 8:07 ` Petr Mladek
2016-04-08 14:34 ` Josh Poimboeuf
2016-04-07 21:15 ` Jessica Yu
2016-04-07 21:37 ` Jiri Kosina
2016-04-07 22:35 ` Josh Poimboeuf
2016-04-07 22:53 ` Jiri Kosina
2016-04-07 23:15 ` Jessica Yu
2016-04-08 7:05 ` Jiri Kosina
2016-04-08 8:03 ` Petr Mladek
2016-04-08 14:31 ` Josh Poimboeuf
2016-04-11 8:38 ` Petr Mladek
2016-03-25 19:34 ` [RFC PATCH v1.9 06/14] x86: add error handling to dump_trace() Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting reliable stack traces Josh Poimboeuf
2016-03-31 13:03 ` Miroslav Benes
2016-04-04 17:54 ` Josh Poimboeuf
2016-04-11 14:16 ` Jiri Slaby
2016-04-12 15:56 ` Josh Poimboeuf
2016-06-09 8:31 ` Jiri Slaby
2016-06-13 21:58 ` Josh Poimboeuf
2016-12-01 20:28 ` Jiri Slaby
2016-12-01 20:59 ` Josh Poimboeuf
2017-01-17 13:08 ` Jiri Slaby
2016-04-04 15:55 ` Petr Mladek
2016-04-04 17:58 ` Josh Poimboeuf
2016-04-07 11:55 ` Petr Mladek
2016-04-07 14:46 ` Josh Poimboeuf
2016-04-08 8:24 ` Petr Mladek
2016-04-11 3:29 ` Jessica Yu
2016-03-25 19:34 ` [RFC PATCH v1.9 08/14] livepatch: separate enabled and patched states Josh Poimboeuf
2016-04-11 3:31 ` Jessica Yu
2016-04-12 14:44 ` [RFC PATCH v1.9 08/14] " Chris J Arges
2016-04-12 17:16 ` Josh Poimboeuf
2016-04-12 17:35 ` Chris J Arges
2016-04-12 18:25 ` Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 09/14] livepatch: remove unnecessary object loaded check Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 10/14] livepatch: move patching functions into patch.c Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 11/14] livepatch: store function sizes Josh Poimboeuf
2016-03-25 19:34 ` [RFC PATCH v1.9 12/14] livepatch: create per-task consistency model Josh Poimboeuf
2016-03-31 13:12 ` Miroslav Benes
2016-04-04 18:21 ` Josh Poimboeuf
2016-04-04 18:27 ` Vojtech Pavlik [this message]
2016-04-04 18:33 ` Josh Poimboeuf
2016-04-05 11:36 ` Vojtech Pavlik
2016-04-05 13:53 ` Josh Poimboeuf
2016-04-05 17:32 ` Minfei Huang
2016-04-05 21:17 ` Josh Poimboeuf
2016-04-14 9:25 ` Miroslav Benes
2016-04-14 16:39 ` Josh Poimboeuf
2016-04-15 9:17 ` Miroslav Benes
2016-03-25 19:35 ` [RFC PATCH v1.9 13/14] livepatch: add /proc/<pid>/patch_status Josh Poimboeuf
2016-03-31 9:33 ` Jiri Slaby
2016-03-31 9:40 ` Jiri Slaby
2016-04-04 16:56 ` Josh Poimboeuf
2016-03-25 19:35 ` [RFC PATCH v1.9 14/14] livepatch: update task universe when exiting kernel Josh Poimboeuf
2016-04-14 8:47 ` Miroslav Benes
2016-04-14 8:50 ` Miroslav Benes
2016-04-14 13:39 ` Josh Poimboeuf
2016-04-18 15:01 ` [RFC PATCH 0/2] s390/klp: s390 support Miroslav Benes
2016-04-18 15:01 ` [RFC PATCH 1/2] s390: livepatch, reorganize TIF bits Miroslav Benes
2016-04-18 15:01 ` [RFC PATCH 2/2] s390/klp: update task universe when exiting kernel Miroslav Benes
2016-04-18 15:17 ` [RFC PATCH 0/2] s390/klp: s390 support Josh Poimboeuf
2016-04-14 13:23 ` [RFC PATCH v1.9 14/14] livepatch: update task universe when exiting kernel Josh Poimboeuf
2016-03-31 12:54 ` [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Miroslav Benes
2016-04-04 17:03 ` Josh Poimboeuf
2016-04-05 14:24 ` Miroslav Benes
2016-04-05 14:34 ` Josh Poimboeuf
2016-04-05 14:53 ` Miroslav Benes
2016-04-01 13:34 ` Miroslav Benes
2016-04-01 13:39 ` Petr Mladek
2016-04-01 15:38 ` Petr Mladek
2016-04-05 13:44 ` Josh Poimboeuf
2016-04-06 8:15 ` Petr Mladek
2016-04-28 18:53 ` Josh Poimboeuf
2016-06-09 14:20 ` Petr Mladek
2016-04-07 12:10 ` Petr Mladek
2016-04-07 15:08 ` Josh Poimboeuf
2016-04-07 15:47 ` Jiri Kosina
2016-04-07 18:03 ` Josh Poimboeuf
2016-04-07 18:33 ` Jiri Kosina
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