On 12/3/24 12:55, Steven Rostedt wrote:
[ Adding MIPS maintainers ]
On Tue, 3 Dec 2024 12:39:08 -0800
Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
Hi Steven,
On Thu, Oct 03, 2024 at 06:16:29PM -0400, Steven Rostedt wrote:
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
The trace_*_rcuidle() variant of a tracepoint was to handle places where a
tracepoint was located but RCU was not "watching". All those locations
have been removed, and RCU should be watching where all tracepoints are
located. We can now remove the trace_*_rcuidle() variant.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
This patch triggers backtraces with mips qemu emulations.
WARNING: CPU: 0 PID: 0 at include/trace/events/preemptirq.h:36 handle_int+0x128/0x178
RCU not watching for tracepoint
...
Call Trace:
[<ffffffff8012a89c>] show_stack+0x64/0x158
[<ffffffff8011e998>] dump_stack_lvl+0xb4/0x128
[<ffffffff801550f4>] __warn+0xa4/0x1f8
[<ffffffff80155328>] warn_slowpath_fmt+0xe0/0x1d0
[<ffffffff801233e8>] handle_int+0x128/0x178
[<ffffffff80f25ff8>] r4k_wait+0x30/0x40
[<ffffffff80f26448>] default_idle_call+0xa0/0x330
[<ffffffff801b6ccc>] do_idle+0xe4/0x1b8
[<ffffffff801b71c4>] cpu_startup_entry+0x34/0x48
[<ffffffff80f2689c>] kernel_init+0x0/0x110
WARNING: CPU: 0 PID: 0 at include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x184/0x240
RCU not watching for tracepoint
...
Call Trace:
[<ffffffff8012a89c>] show_stack+0x64/0x158
[<ffffffff8011e998>] dump_stack_lvl+0xb4/0x128
[<ffffffff801550f4>] __warn+0xa4/0x1f8
[<ffffffff80155328>] warn_slowpath_fmt+0xe0/0x1d0
[<ffffffff8028fb74>] trace_hardirqs_on+0x184/0x240
[<ffffffff80123030>] restore_partial+0x6c/0x13c
Bisect log is attached.
I'm guessing MIPS needs to implement something like what arm64 did with:
7cd1ea1010acb ("arm64: entry: fix non-NMI kernel<->kernel transitions")
Because we do not want to bring back the trace_*_rcuidle() crap.
Hmm. If you say so. Note that powerpc has the same or a similar problem.
[ 0.142039][ T0] RCU not watching for tracepoint
[ 0.142488][ T0]
[ 0.142659][ T0] =============================
[ 0.142755][ T0] WARNING: suspicious RCU usage
[ 0.142914][ T0] 6.13.0-rc1-00058-ge75ce84aa5d3 #1 Not tainted
[ 0.143082][ T0] -----------------------------
[ 0.143178][ T0] kernel/notifier.c:586 notify_die called but RCU thinks we're quiescent!
[ 0.152733][ T0] RCU not watching for tracepoint
[ 0.152770][ T0]
[ 0.152995][ T0] =============================
[ 0.153092][ T0] WARNING: suspicious RCU usage
[ 0.153187][ T0] 6.13.0-rc1-00058-ge75ce84aa5d3 #1 Not tainted
[ 0.153301][ T0] -----------------------------
[ 0.153394][ T0] include/linux/rcupdate.h:850 rcu_read_lock() used illegally while idle!
[ 0.165396][ T0] RCU not watching for tracepoint
[ 0.165540][ T0]
[ 0.165712][ T0] =============================
[ 0.165811][ T0] WARNING: suspicious RCU usage
[ 0.165909][ T0] 6.13.0-rc1-00058-ge75ce84aa5d3 #1 Not tainted
[ 0.166026][ T0] -----------------------------
[ 0.166122][ T0] include/linux/rcupdate.h:878 rcu_read_unlock() used illegally while idle!
and many more.
Guenter
