next/pending-fixes bisection: baseline.login on bcm2836-rpi-2-b
Jason A. Donenfeld
Jason at zx2c4.com
Mon Oct 10 05:50:54 PDT 2022
On Mon, Oct 10, 2022 at 12:59:41PM +0100, Mark Brown wrote:
> The KernelCI bisection bot found a boot failure on Raspberry Pi 2B with
> multi_v7_defconfig+CONFIG_THUMB2_KERNEL on next/pending-fixes triggered
> by b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted
> sources"). A RCU stall is detected towards the end of boot reading from
> the bcm2835 hwrng:
>
> <6>[ 3.362859] Freeing initrd memory: 16196K
> <3>[ 23.160131] rcu: INFO: rcu_sched self-detected stall on CPU
> <3>[ 23.166057] rcu: 0-....: (2099 ticks this GP) idle=03b4/1/0x40000002 softirq=28/28 fqs=1050
> <4>[ 23.174895] (t=2101 jiffies g=-1147 q=2353 ncpus=4)
> <4>[ 23.180203] CPU: 0 PID: 49 Comm: hwrng Not tainted 6.0.0 #1
> <4>[ 23.186125] Hardware name: BCM2835
> <4>[ 23.189837] PC is at bcm2835_rng_read+0x30/0x6c
> <4>[ 23.194709] LR is at hwrng_fillfn+0x71/0xf4
> <4>[ 23.199218] pc : [<c07ccdc8>] lr : [<c07cb841>] psr: 40000033
> <4>[ 23.205840] sp : f093df70 ip : 00000000 fp : 00000000
> <4>[ 23.211404] r10: c3c7e800 r9 : 00000000 r8 : c17e6b20
> <4>[ 23.216968] r7 : c17e6b64 r6 : c18b0a74 r5 : c07ccd99 r4 : c3f171c0
> <4>[ 23.223855] r3 : 000fffff r2 : 00000040 r1 : c3c7e800 r0 : c3f171c0
> <4>[ 23.230743] Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment none
> <4>[ 23.238426] Control: 50c5387d Table: 0020406a DAC: 00000051
> <4>[ 23.244519] CPU: 0 PID: 49 Comm: hwrng Not tainted 6.0.0 #1
In drivers/char/hw_random/bcm2835-rng.c, if you replace the cpu_relax()
with hwrng_msleep(rng, 1000), does it fix the problem?
Jason
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