From: Chris Metcalf <cmetcalf@mellanox.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Gilad Ben Yossef <giladb@ezchip.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Christoph Lameter <cl@linux.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@amacapital.net>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v10 07/12] task_isolation: add debug boot flag
Date: Wed, 2 Mar 2016 15:56:27 -0500 [thread overview]
Message-ID: <56D7537B.5040804@mellanox.com> (raw)
In-Reply-To: <20160302203748.GH6356@twins.programming.kicks-ass.net>
On 3/2/2016 3:37 PM, Peter Zijlstra wrote:
> On Wed, Mar 02, 2016 at 03:09:31PM -0500, Chris Metcalf wrote:
>> +void task_isolation_debug(int cpu)
>> +{
>> + struct task_struct *p;
>> +
>> + if (!task_isolation_possible(cpu))
>> + return;
>> +
>> + rcu_read_lock();
>> + p = cpu_curr(cpu);
>> + get_task_struct(p);
> As I think Oleg keeps reminding me, this is not actually a safe thing to
> do.
So what's the right solution? The fast path in task_isolation_debug_task basically
just uses the new "task_isolation_flags", and "pid" and "comm". I would think those
would all have to be safe because of the get_task_struct().
The piece that might be problematic is the eventual call to send_sig_info() using the
task_struct pointer (called via task_isolation_debug_task -> task_isolation_interrupt).
Clearly this is safe at some level, since that's more or less what sys_kill() does and the
process could similarly evaporate half way through sending the signal.
Suggestions? Thanks!
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
next prev parent reply other threads:[~2016-03-02 20:56 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 20:09 [PATCH v10 00/12] support "task_isolation" mode Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 01/12] vmstat: add quiet_vmstat_sync function Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 02/12] vmstat: add vmstat_idle function Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 03/12] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 04/12] task_isolation: add initial support Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 05/12] task_isolation: support CONFIG_TASK_ISOLATION_ALL Chris Metcalf
2016-03-03 18:34 ` Andi Kleen
2016-03-03 19:40 ` Chris Metcalf
2016-03-03 20:04 ` Andi Kleen
2016-03-05 12:31 ` Ingo Molnar
2016-03-02 20:09 ` [PATCH v10 06/12] task_isolation: support PR_TASK_ISOLATION_STRICT mode Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 07/12] task_isolation: add debug boot flag Chris Metcalf
2016-03-02 20:37 ` Peter Zijlstra
2016-03-02 20:56 ` Chris Metcalf [this message]
2016-03-02 20:09 ` [PATCH v10 08/12] arm, tile: turn off timer tick for oneshot_stopped state Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 09/12] arch/x86: enable task isolation functionality Chris Metcalf
2016-03-03 0:36 ` Andy Lutomirski
2016-03-03 19:52 ` Chris Metcalf
2016-03-03 23:46 ` Andy Lutomirski
2016-03-07 20:51 ` Chris Metcalf
2016-03-07 20:55 ` Andy Lutomirski
2016-03-08 20:40 ` Chris Metcalf
2016-03-09 20:58 ` Andy Lutomirski
2016-03-09 21:05 ` Chris Metcalf
2016-03-09 21:07 ` Andy Lutomirski
2016-03-09 21:13 ` Chris Metcalf
2016-03-09 21:10 ` Kees Cook
2016-03-09 21:18 ` Andy Lutomirski
2016-03-09 21:25 ` Kees Cook
2016-03-09 21:57 ` Andy Lutomirski
2016-03-02 20:09 ` [PATCH v10 10/12] arch/tile: " Chris Metcalf
2016-03-02 20:09 ` [PATCH v10 11/12] arm64: factor work_pending state machine to C Chris Metcalf
2016-03-04 16:38 ` Will Deacon
2016-03-04 20:02 ` Chris Metcalf
2016-03-14 10:29 ` Mark Rutland
2016-03-02 20:09 ` [PATCH v10 12/12] arch/arm64: enable task isolation functionality Chris Metcalf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=56D7537B.5040804@mellanox.com \
--to=cmetcalf@mellanox.com \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=cl@linux.com \
--cc=fweisbec@gmail.com \
--cc=giladb@ezchip.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=viresh.kumar@linaro.org \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).