From: Masami Hiramatsu <mhiramat@kernel.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Anders Roxell <anders.roxell@linaro.org>,
paulmck@kernel.org, "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
David Miller <davem@davemloft.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -tip V2 0/2] kprobes: Fix RCU warning and cleanup
Date: Sat, 11 Jan 2020 08:35:07 +0900 [thread overview]
Message-ID: <20200111083507.c32b85b1d47aa69928de530b@kernel.org> (raw)
In-Reply-To: <20200110211438.GE128013@google.com>
Hi Joel and Paul,
On Fri, 10 Jan 2020 16:14:38 -0500
Joel Fernandes <joel@joelfernandes.org> wrote:
> On Tue, Jan 07, 2020 at 09:15:35PM +0900, Masami Hiramatsu wrote:
> > Hello,
> >
> > Anyone have any comment on this series?
> > Without this series, I still see the suspicious RCU warning for kprobe on -tip tree.
>
> +Paul since RCU.
>
> Hi Masami,
>
> I believe I had commented before that I don't agree with this patch:
> https://lore.kernel.org/lkml/157535318870.16485.6366477974356032624.stgit@devnote2/
>
> The rationale you used is to replace RCU-api with non-RCU api just to avoid
> warnings. I think a better approach is to use RCU api and pass the optional
> expression to silence the false-positive warnings by informing the RCU API
> about the fact that locks are held (similar to what we do for
> rcu_dereference_protected()). The RCU API will do additional checking
> (such as making sure preemption is disabled for safe RCU usage etc) as well.
Yes, that is what I did in [1/2] for get_kprobe().
Let me clarify the RCU list usage in [2/2].
With the careful check, other list traversals never be done in non-sleepable
context, those are always runs with kprobe_mutex held.
If I correctly understand the Documentation/RCU/listRCU.rst, we should/can use
non-RCU api for those cases, or do I miss something?
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2020-01-10 23:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 6:06 [PATCH -tip V2 0/2] kprobes: Fix RCU warning and cleanup Masami Hiramatsu
2019-12-03 6:06 ` [PATCH -tip V2 1/2] kprobes: Suppress the suspicious RCU warning on kprobes Masami Hiramatsu
2019-12-03 6:06 ` [PATCH -tip V2 2/2] kprobes: Use non RCU traversal APIs on kprobe_tables if possible Masami Hiramatsu
2020-01-14 13:56 ` Joel Fernandes
2020-01-15 1:31 ` Masami Hiramatsu
2019-12-20 18:55 ` [PATCH -tip V2 0/2] kprobes: Fix RCU warning and cleanup Masami Hiramatsu
2020-01-07 12:15 ` Masami Hiramatsu
2020-01-10 21:14 ` Joel Fernandes
2020-01-10 23:35 ` Masami Hiramatsu [this message]
2020-01-12 2:05 ` Joel Fernandes
2020-01-13 3:16 ` Masami Hiramatsu
2020-01-13 13:09 ` Masami Hiramatsu
2020-01-13 19:23 ` Paul E. McKenney
2020-01-14 11:49 ` Masami Hiramatsu
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=20200111083507.c32b85b1d47aa69928de530b@kernel.org \
--to=mhiramat@kernel.org \
--cc=anders.roxell@linaro.org \
--cc=anil.s.keshavamurthy@intel.com \
--cc=davem@davemloft.net \
--cc=joel@joelfernandes.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=naveen.n.rao@linux.ibm.com \
--cc=paulmck@kernel.org \
/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).