| Message ID | 20221115204847.593616-1-gpiccoli@igalia.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d0b24b4e91fcb8408c4979888547f86be514e337 |
| Headers | show |
| Series | ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels | expand |
On Tue, 15 Nov 2022 17:48:47 -0300 "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > The function match_records() may take a while due to a large > number of string comparisons, so when in PREEMPT_VOLUNTARY > kernels we could face RCU stalls due to that. > > Add a cond_resched() to prevent that. > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > Acked-by: Paul E. McKenney <paulmck@kernel.org> # from RCU CPU stall warning perspective > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> This looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thanks! > --- > > Hi Steve / Paul, thanks for the discussions on the first thread [0], > much appreciated! Here is the "official" version. > > Steve: lemme know if it's good for you, and in case you prefer to > send it yourself (since you proposed it on IRC), fine by me! > > Paul: kept your ACK (thanks for that BTW) even though I changed the > place of cond_resched() to align with Steve's preference. Lemme know > in case you want to drop this ACK. > > Cheers, > > Guilherme > > > [0] https://lore.kernel.org/lkml/1ef5fe19-a82f-835e-fda5-455e9c2b94b4@igalia.com/ > > > kernel/trace/ftrace.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 7dc023641bf1..80639bdb85f6 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -4192,6 +4192,7 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod) > } > found = 1; > } > + cond_resched(); > } while_for_each_ftrace_rec(); > out_unlock: > mutex_unlock(&ftrace_lock); > -- > 2.38.0 >
On 16/11/2022 03:36, Masami Hiramatsu (Google) wrote: > [...] > This looks good to me. > > Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Thanks! Thanks for your review/Ack Masami, much appreciated. Cheers, Guilherme
On 16/11/2022 03:36, Masami Hiramatsu (Google) wrote: > On Tue, 15 Nov 2022 17:48:47 -0300 > "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > >> The function match_records() may take a while due to a large >> number of string comparisons, so when in PREEMPT_VOLUNTARY >> kernels we could face RCU stalls due to that. >> >> Add a cond_resched() to prevent that. >> >> Suggested-by: Steven Rostedt <rostedt@goodmis.org> >> Acked-by: Paul E. McKenney <paulmck@kernel.org> # from RCU CPU stall warning perspective >> Cc: Masami Hiramatsu <mhiramat@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> > > This looks good to me. > > Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Thanks! > Hi Steve, apologies for the ping, just want to ask you if you plan to take this one or should I change something? Thanks in advance, Guilherme
On Tue, 22 Nov 2022 10:16:41 -0300 "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > Hi Steve, apologies for the ping, just want to ask you if you plan to > take this one or should I change something? Thanks in advance, I was traveling for work from Oct 31-Nov 14 and when I got back, I had over 300 patches to review in my queue. I'm now down under 100, so hopefully I can get to it soon. Just may take a bit. Thanks, -- Steve
On 22/11/2022 12:49, Steven Rostedt wrote: > [...] > I was traveling for work from Oct 31-Nov 14 and when I got back, I had over > 300 patches to review in my queue. I'm now down under 100, so hopefully I > can get to it soon. > > Just may take a bit. > > Thanks, > > -- Steve No hurries, thanks for your heads-up! Cheers, Guilherme
On 16/11/2022 03:36, Masami Hiramatsu (Google) wrote: > On Tue, 15 Nov 2022 17:48:47 -0300 > "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > >> The function match_records() may take a while due to a large >> number of string comparisons, so when in PREEMPT_VOLUNTARY >> kernels we could face RCU stalls due to that. >> >> Add a cond_resched() to prevent that. >> >> Suggested-by: Steven Rostedt <rostedt@goodmis.org> >> Acked-by: Paul E. McKenney <paulmck@kernel.org> # from RCU CPU stall warning perspective >> Cc: Masami Hiramatsu <mhiramat@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> > > This looks good to me. > > Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Thanks! > Hi Steve, sorry to annoy, just a regular ping to see if we can get this into 6.2 (if too late, not a huge deal). Thanks, Guilherme
On Tue, 13 Dec 2022 19:04:41 -0300 "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > Hi Steve, sorry to annoy, just a regular ping to see if we can get this > into 6.2 (if too late, not a huge deal). Thanks for the ping. For some reason this patch didn't make it into my internal Patchwork, so I missed it (even though I did reply to you, I just assumed it was in my patchwork). It's not too late. I have some last minute patches I'm still testing. I'll queue this one up. BTW, we now have a kernel ftrace mailing list that you can Cc (but still Cc LKML). linux-trace-kernel@vger.kernel.org -- Steve
On 13/12/2022 19:34, Steven Rostedt wrote: > On Tue, 13 Dec 2022 19:04:41 -0300 > "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote: > >> Hi Steve, sorry to annoy, just a regular ping to see if we can get this >> into 6.2 (if too late, not a huge deal). > > Thanks for the ping. For some reason this patch didn't make it into my > internal Patchwork, so I missed it (even though I did reply to you, I just > assumed it was in my patchwork). > > It's not too late. I have some last minute patches I'm still testing. I'll > queue this one up. > > BTW, we now have a kernel ftrace mailing list that you can Cc (but still Cc > LKML). > > linux-trace-kernel@vger.kernel.org > > -- Steve Tnx a lot Steve! I'll start to CC this list as well. Cheers, Guilherme
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7dc023641bf1..80639bdb85f6 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4192,6 +4192,7 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod) } found = 1; } + cond_resched(); } while_for_each_ftrace_rec(); out_unlock: mutex_unlock(&ftrace_lock);