On 2022-05-06 6:34 p.m., John David Anglin wrote:
On 2022-05-06 5:30 p.m., John David Anglin wrote:
I've built 5.17.5 (32bit). Boots ok on c3000. No segfaults.
But I do see the stalls as well:
...
Starting Avahi mDNS/DNS-SD Daemon: avahi-daemon.
Starting periodic command scheduler: cron.
[ 31.472708] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[ 31.543577] (detected by 0, t=2102 jiffies, g=7361, q=10)
[ 31.609191] rcu: All QSes seen, last rcu_sched kthread activity 2102 (-22271--24373), jiffies_till_next_fqs=1, root ->qsmask 0x0
[ 31.747614] rcu: rcu_sched kthread starved for 2102 jiffies! g7361 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
[ 31.867313] rcu: Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior.
[ 31.974535] rcu: RCU grace-period kthread stack dump:
[ 32.034962] task:rcu_sched state:R running task stack: 0 pid: 10 ppid: 2 flags:0x00000000
[ 32.153733] Backtrace:
[ 32.181916] [<1094c21c>] __schedule+0x2dc/0x964
[ 32.237240] [<1094c90c>] schedule+0x68/0x138
[ 32.289340] [<10953068>] schedule_timeout+0x84/0x178
[ 32.349762] [<102472b4>] rcu_gp_fqs_loop+0x32c/0x428
[ 32.410186] [<10249660>] rcu_gp_kthread+0x10c/0x1e8
[ 32.469569] [<101ebc98>] kthread+0x100/0x108
[ 32.521674] [<1019b01c>] ret_from_kernel_thread+0x1c/0x24
ARGH!!!
This was introduced by the following commit:
commit d97180ad68bdb7ee10f327205a649bc2f558741d
Author: Helge Deller <deller@xxxxxx>
Date: Wed Sep 8 23:27:00 2021 +0200
parisc: Mark sched_clock unstable only if clocks are not syncronized
We check at runtime if the cr16 clocks are stable across CPUs. Only mark
the sched_clock unstable by calling clear_sched_clock_stable() if we
know that we run on a system which isn't syncronized across CPUs.
Signed-off-by: Helge Deller <deller@xxxxxx>
In searching for the cause, I also noticed this commit:
commit e4f2006f1287e7ea17660490569cff323772dac4
Author: Helge Deller <deller@xxxxxx>
Date: Tue Sep 7 05:03:29 2021 +0200
parisc: Reduce sigreturn trampoline to 3 instructions
We can move the INSN_LDI_R20 instruction into the branch delay slot.
Signed-off-by: Helge Deller <deller@xxxxxx>
Changing the sigreturn trampoline breaks gdb's detection of signal frames.
I suspect the INSN_LDI_R20 instruction was intentionally put before the
branch to make the sequence more unique.
It appears the latter commit has been reverted. The former commit has been modified.
32bit v5.15.37 boots successfully if setup.c and time.c are reverted to v5.14. Otherwise,
boot stalls as above.
Dave
--
John David Anglin dave.anglin@xxxxxxxx
