[ 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.
-- Steve
>
> Guenter
>
> ---
> # bad: [f6420e2ee9caa3ecf226d0db22572db0d9451977] Merge branch 'fixes-v6.13' into testing
> # good: [adc218676eef25575469234709c2d87185ca223a] Linux 6.12
> git bisect start 'f6420e2ee9ca' 'v6.12'
> # good: [6e95ef0258ff4ee23ae3b06bf6b00b33dbbd5ef7] Merge tag 'bpf-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
> git bisect good 6e95ef0258ff4ee23ae3b06bf6b00b33dbbd5ef7
> # good: [071b34dcf71523a559b6c39f5d21a268a9531b50] Merge tag 'sound-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
> git bisect good 071b34dcf71523a559b6c39f5d21a268a9531b50
> # good: [8a07b2623e7ff04856f8d4470d002675049b2065] Merge tag 'drm-misc-next-2024-10-31' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-next
> git bisect good 8a07b2623e7ff04856f8d4470d002675049b2065
> # bad: [80739fd00c7ea1315d362ce889bef499452913ef] Merge tag 'mfd-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd
> git bisect bad 80739fd00c7ea1315d362ce889bef499452913ef
> # good: [e175800137f588688ac6aae30ce491e098f30c45] Merge tag 'exynos-drm-next-for-v6.13-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos into drm-next
> git bisect good e175800137f588688ac6aae30ce491e098f30c45
> # good: [ade5add00da20de40f63d097345bddea24d924f4] Merge tag 'amd-drm-next-6.13-2024-11-15' of https://gitlab.freedesktop.org/agd5f/linux into drm-next
> git bisect good ade5add00da20de40f63d097345bddea24d924f4
> # bad: [06afb0f36106ecb839c5e2509905e68c1e2677de] Merge tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
> git bisect bad 06afb0f36106ecb839c5e2509905e68c1e2677de
> # good: [f1db825805d48cee6826b7dc082a04112c1f0c8d] Merge tag 'trace-ring-buffer-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
> git bisect good f1db825805d48cee6826b7dc082a04112c1f0c8d
> # bad: [61c6fefa92bb4ed7a34163b94f6ffac628237a29] bpf: decouple BPF link/attach hook and BPF program sleepable semantics
> git bisect bad 61c6fefa92bb4ed7a34163b94f6ffac628237a29
> # bad: [cdb537ac417938408ee819992f432c410f2d01a2] tracing/perf: Add might_fault check to syscall probes
> git bisect bad cdb537ac417938408ee819992f432c410f2d01a2
> # bad: [e53244e2c8931f9e80c1841293aea86ef8ad32a3] tracepoint: Remove SRCU protection
> git bisect bad e53244e2c8931f9e80c1841293aea86ef8ad32a3
> # good: [49e4154f4b16345da5e219b23ed9737a6e735bc1] tracing: Remove TRACE_EVENT_FL_FILTERED logic
> git bisect good 49e4154f4b16345da5e219b23ed9737a6e735bc1
> # bad: [48bcda6848232667f13b4e97588de488c83c37d4] tracing: Remove definition of trace_*_rcuidle()
> git bisect bad 48bcda6848232667f13b4e97588de488c83c37d4
> # good: [4a8840af5f53f2902eba91130fae650879f18e7a] tracepoints: Use new static branch API
> git bisect good 4a8840af5f53f2902eba91130fae650879f18e7a
> # first bad commit: [48bcda6848232667f13b4e97588de488c83c37d4] tracing: Remove definition of trace_*_rcuidle()
