From: Frederic Weisbecker <fweisbec@gmail.com>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: paulmck@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, paulus@samba.org
Subject: Re: [RFC PATCH 1/5] powerpc: Syscall hooks for context tracking subsystem
Date: Thu, 7 Feb 2013 17:09:43 +0100 [thread overview]
Message-ID: <CAFTL4hwTqm541NfMjuF9kiUR6+PuMMnb5TnXzvEZieRgjggYgw@mail.gmail.com> (raw)
In-Reply-To: <1360227230.13550.23.camel@ThinkPad-T5421.cn.ibm.com>
2013/2/7 Li Zhong <zhong@linux.vnet.ibm.com>:
> On Thu, 2013-02-07 at 01:29 +0100, Frederic Weisbecker wrote:
>> In x86-64, schedule_user() and do_notify_resume() can be called before
>> syscall_trace_leave(). As a result we may be entering
>> syscall_trace_leave() in user mode (from a context tracking POV). To
>> fix this I added a call to user_exit() on the very beginning of that
>> function.
>>
>> You can find the details in 2c5594df344cd1ff0cc9bf007dea3235582b3acf
>> ("rcu: Fix unrecovered RCU user mode in syscall_trace_leave()").
>
> Hi Frederic,
>
> Thank you very much for the reminding.
>
>>
>> Could this problem happen in ppc as well?
>
> I checked the code(64 bit) today, it seems to me that it won't happen.
> But fortunately, we are in the ppc mailing list, please correct me if my
> understanding is wrong.
Ah indeed. Looking at syscall_exit_work label in entry_64.S,
do_syscall_trace_leave is called before ret_from_except which is where
we handle user preemption and do_notify_resume. So that looks fine.
>
> By the way, I enabled CONTEXT_TRACKING_FORCE and PROVE_RCU, so if it
> could happen, I think there should be some illegal RCU usage complaints
> reported.
Ok.
Thanks.
next prev parent reply other threads:[~2013-02-07 16:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-01 10:27 [RFC PATCH 0/5] powerpc: Support context tracking for Power pSeries Li Zhong
2013-02-01 10:27 ` [RFC PATCH 1/5] powerpc: Syscall hooks for context tracking subsystem Li Zhong
2013-02-07 0:29 ` Frederic Weisbecker
2013-02-07 8:53 ` Li Zhong
2013-02-07 16:09 ` Frederic Weisbecker [this message]
2013-02-10 10:32 ` Frederic Weisbecker
2013-02-01 10:27 ` [RFC PATCH 2/5] powerpc: Exception " Li Zhong
2013-02-10 14:10 ` Frederic Weisbecker
2013-02-16 9:41 ` Li Zhong
2013-02-01 10:27 ` [RFC PATCH 3/5] powerpc: Exit user context on notify resume Li Zhong
2013-02-01 10:27 ` [RFC PATCH 4/5] powerpc: Use the new schedule_user API on userspace preemption Li Zhong
2013-02-01 10:27 ` [RFC PATCH 5/5] powerpc: select HAVE_CONTEXT_TRACKING for pSeries Li Zhong
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=CAFTL4hwTqm541NfMjuF9kiUR6+PuMMnb5TnXzvEZieRgjggYgw@mail.gmail.com \
--to=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=paulus@samba.org \
--cc=zhong@linux.vnet.ibm.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).