diff options
| author | Cristian Marussi <cristian.marussi@arm.com> | 2020-03-11 20:12:44 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-03-18 01:51:18 +0300 |
| commit | d0bab0c39e32d39a8c5cddca72e5b4a3059fe050 (patch) | |
| tree | 8f387f5370ae1a4810125af1f49b03599ceddd6a /arch | |
| parent | 9abd515a6e4a5c58c6eb4d04110430325eb5f5ac (diff) | |
| download | linux-d0bab0c39e32d39a8c5cddca72e5b4a3059fe050.tar.xz | |
arm64: smp: fix smp_send_stop() behaviour
On a system with only one CPU online, when another one CPU panics while
starting-up, smp_send_stop() will fail to send any STOP message to the
other already online core, resulting in a system still responsive and
alive at the end of the panic procedure.
[ 186.700083] CPU3: shutdown
[ 187.075462] CPU2: shutdown
[ 187.162869] CPU1: shutdown
[ 188.689998] ------------[ cut here ]------------
[ 188.691645] kernel BUG at arch/arm64/kernel/cpufeature.c:886!
[ 188.692079] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 188.692444] Modules linked in:
[ 188.693031] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.6.0-rc4-00001-g338d25c35a98 #104
[ 188.693175] Hardware name: Foundation-v8A (DT)
[ 188.693492] pstate: 200001c5 (nzCv dAIF -PAN -UAO)
[ 188.694183] pc : has_cpuid_feature+0xf0/0x348
[ 188.694311] lr : verify_local_elf_hwcaps+0x84/0xe8
[ 188.694410] sp : ffff800011b1bf60
[ 188.694536] x29: ffff800011b1bf60 x28: 0000000000000000
[ 188.694707] x27: 0000000000000000 x26: 0000000000000000
[ 188.694801] x25: 0000000000000000 x24: ffff80001189a25c
[ 188.694905] x23: 0000000000000000 x22: 0000000000000000
[ 188.694996] x21: ffff8000114aa018 x20: ffff800011156a38
[ 188.695089] x19: ffff800010c944a0 x18: 0000000000000004
[ 188.695187] x17: 0000000000000000 x16: 0000000000000000
[ 188.695280] x15: 0000249dbde5431e x14: 0262cbe497efa1fa
[ 188.695371] x13: 0000000000000002 x12: 0000000000002592
[ 188.695472] x11: 0000000000000080 x10: 00400032b5503510
[ 188.695572] x9 : 0000000000000000 x8 : ffff800010c80204
[ 188.695659] x7 : 00000000410fd0f0 x6 : 0000000000000001
[ 188.695750] x5 : 00000000410fd0f0 x4 : 0000000000000000
[ 188.695836] x3 : 0000000000000000 x2 : ffff8000100939d8
[ 188.695919] x1 : 0000000000180420 x0 : 0000000000180480
[ 188.696253] Call trace:
[ 188.696410] has_cpuid_feature+0xf0/0x348
[ 188.696504] verify_local_elf_hwcaps+0x84/0xe8
[ 188.696591] check_local_cpu_capabilities+0x44/0x128
[ 188.696666] secondary_start_kernel+0xf4/0x188
[ 188.697150] Code: 52805001 72a00301 6b01001f 54000ec0 (d4210000)
[ 188.698639] ---[ end trace 3f12ca47652f7b72 ]---
[ 188.699160] Kernel panic - not syncing: Attempted to kill the idle task!
[ 188.699546] Kernel Offset: disabled
[ 188.699828] CPU features: 0x00004,20c02008
[ 188.700012] Memory Limit: none
[ 188.700538] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
[root@arch ~]# echo Helo
Helo
[root@arch ~]# cat /proc/cpuinfo | grep proce
processor : 0
Make smp_send_stop() account also for the online status of the calling CPU
while evaluating how many CPUs are effectively online: this way, the right
number of STOPs is sent, so enforcing a proper freeze of the system at the
end of panic even under the above conditions.
Fixes: 08e875c16a16c ("arm64: SMP support")
Reported-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/smp.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index d4ed9a19d8fe..e4dc241c5a8e 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -958,11 +958,22 @@ void tick_broadcast(const struct cpumask *mask) } #endif +/* + * The number of CPUs online, not counting this CPU (which may not be + * fully online and so not counted in num_online_cpus()). + */ +static inline unsigned int num_other_online_cpus(void) +{ + unsigned int this_cpu_online = cpu_online(smp_processor_id()); + + return num_online_cpus() - this_cpu_online; +} + void smp_send_stop(void) { unsigned long timeout; - if (num_online_cpus() > 1) { + if (num_other_online_cpus()) { cpumask_t mask; cpumask_copy(&mask, cpu_online_mask); @@ -975,10 +986,10 @@ void smp_send_stop(void) /* Wait up to one second for other CPUs to stop */ timeout = USEC_PER_SEC; - while (num_online_cpus() > 1 && timeout--) + while (num_other_online_cpus() && timeout--) udelay(1); - if (num_online_cpus() > 1) + if (num_other_online_cpus()) pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", cpumask_pr_args(cpu_online_mask)); |