Messages in this thread | | | Date | Thu, 15 Jun 2023 15:21:02 +0200 | From | Francesco Dolcini <> | Subject | Re: [PATCH v6 1/5] kernel/reboot: emergency_restart: set correct system_state |
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Hello Nishanth,
On Wed, Jun 14, 2023 at 07:06:50PM -0500, Nishanth Menon wrote: > On 21:02-20230509, Benjamin Bara wrote: > > From: Benjamin Bara <benjamin.bara@skidata.com> > > > > As the emergency restart does not call kernel_restart_prepare(), the > > system_state stays in SYSTEM_RUNNING. > > > > Since bae1d3a05a8b, this hinders i2c_in_atomic_xfer_mode() from becoming > > active, and therefore might lead to avoidable warnings in the restart > > handlers, e.g.: > > > > [ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0 > > [ 12.676926] Voluntary context switch within RCU read-side critical section! > > ... > > [ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114 > > [ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70 > > ... > > [ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58 > > [ 13.001050] machine_restart from panic+0x2a8/0x32c > > > > Avoid these by setting the correct system_state. > > > > Fixes: bae1d3a05a8b ("i2c: core: remove use of in_atomic()") > > Cc: stable@vger.kernel.org # v5.2+ > > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > > --- > > kernel/reboot.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/kernel/reboot.c b/kernel/reboot.c > > index 3bba88c7ffc6..6ebef11c8876 100644 > > --- a/kernel/reboot.c > > +++ b/kernel/reboot.c > > @@ -74,6 +74,7 @@ void __weak (*pm_power_off)(void); > > void emergency_restart(void) > > { > > kmsg_dump(KMSG_DUMP_EMERG); > > + system_state = SYSTEM_RESTART; > > machine_emergency_restart(); > > } > > EXPORT_SYMBOL_GPL(emergency_restart); > > > > -- > > 2.34.1 > > > > Tested-by: Nishanth Menon <nm@ti.com> > > This in addition to a deeper bug in our driver seems to have helped > resolve a report we had been looking at. Tested on beagleplay platform > > https://lore.kernel.org/all/ZGeHMjlnob2GFyHF@francesco-nb.int.toradex.com/
Is this patch going to fix the RCU warning I reported on that email or it is just part of a more complex solution?
Francesco
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