From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com, Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH] perf: Fix missing SIGTRAPs due to pending_disable abuse
Date: Wed, 5 Oct 2022 10:23:49 +0200 [thread overview]
Message-ID: <Yz0/FfW4kwSK/p9c@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <Yz00IjTZjlsKlNvy@hirez.programming.kicks-ass.net>
On Wed, Oct 05, 2022 at 09:37:06AM +0200, Peter Zijlstra wrote:
> On Tue, Oct 04, 2022 at 07:33:55PM +0200, Marco Elver wrote:
> > It looks reasonable, but obviously needs to pass tests. :-)
>
> Ikr :-)
>
> > Also, see comment below (I think you're still turning signals
> > asynchronous, which we shouldn't do).
>
> Indeed so; I tried fixing that this morning, but so far that doesn't
> seem to want to actually cure things :/ I'll need to stomp on this
> harder.
>
> Current hackery below. The main difference is that instead of trying to
> restart the irq_work on sched_in, sched_out will now queue a task-work.
>
> The event scheduling is done from 'regular' IRQ context and as such
> there should be a return-to-userspace for the relevant task in the
> immediate future (either directly or after scheduling).
>
> Alas, something still isn't right...
Oh, lol, *groan*... this fixes it:
Now to find a sane way to inhibit this while a sig thing is pending :/
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b981b879bcd8..92b6a2f6de1a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3426,7 +3434,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
*/
raw_spin_lock(&ctx->lock);
raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
- if (context_equiv(ctx, next_ctx)) {
+ if (0 && context_equiv(ctx, next_ctx)) {
WRITE_ONCE(ctx->task, next);
WRITE_ONCE(next_ctx->task, task);
next prev parent reply other threads:[~2022-10-05 8:24 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-27 12:13 [PATCH] perf: Fix missing SIGTRAPs due to pending_disable abuse Marco Elver
2022-09-27 12:30 ` Marco Elver
2022-09-27 18:20 ` Peter Zijlstra
2022-09-27 21:45 ` Marco Elver
2022-09-28 10:06 ` Marco Elver
2022-09-28 14:55 ` Marco Elver
2022-10-04 17:09 ` Peter Zijlstra
2022-10-04 17:21 ` Peter Zijlstra
2022-10-04 17:33 ` Marco Elver
2022-10-05 7:37 ` Peter Zijlstra
2022-10-05 7:49 ` Marco Elver
2022-10-05 8:23 ` Peter Zijlstra [this message]
2022-10-06 13:33 ` [PATCH] perf: Fix missing SIGTRAPs Peter Zijlstra
2022-10-06 13:59 ` Marco Elver
2022-10-06 16:02 ` Peter Zijlstra
2022-10-07 9:37 ` Marco Elver
2022-10-07 13:09 ` Peter Zijlstra
2022-10-07 13:58 ` Marco Elver
2022-10-07 16:14 ` Marco Elver
2022-10-08 8:41 ` Marco Elver
2022-10-08 12:41 ` Peter Zijlstra
2022-10-10 20:52 ` Marco Elver
2022-10-08 13:51 ` Peter Zijlstra
2022-10-08 14:08 ` Peter Zijlstra
2022-10-11 7:44 ` [PATCH v2] " Peter Zijlstra
2022-10-11 12:58 ` Marco Elver
2022-10-11 13:06 ` Peter Zijlstra
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=Yz0/FfW4kwSK/p9c@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=acme@kernel.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=dvyukov@google.com \
--cc=elver@google.com \
--cc=jolsa@kernel.org \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=namhyung@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).