From: Jisheng Zhang <[email protected]>
Pin the task's stack before calling walk_stackframe() in get_wchan().
This can fix the panic as reported by Andreas when CONFIG_VMAP_STACK=y:
[ 65.609696] Unable to handle kernel paging request at virtual address ffffffd0003bbde8
[ 65.610460] Oops [#1]
[ 65.610626] Modules linked in: virtio_blk virtio_mmio rtc_goldfish btrfs blake2b_generic libcrc32c xor raid6_pq sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua efivarfs
[ 65.611670] CPU: 2 PID: 1 Comm: systemd Not tainted 5.14.0-rc1-1.g34fe32a-default #1 openSUSE Tumbleweed (unreleased) c62f7109153e5a0897ee58ba52393ad99b070fd2
[ 65.612334] Hardware name: riscv-virtio,qemu (DT)
[ 65.613008] epc : get_wchan+0x5c/0x88
[ 65.613334] ra : get_wchan+0x42/0x88
[ 65.613625] epc : ffffffff800048a4 ra : ffffffff8000488a sp : ffffffd00021bb90
[ 65.614008] gp : ffffffff817709f8 tp : ffffffe07fe91b80 t0 : 00000000000001f8
[ 65.614411] t1 : 0000000000020000 t2 : 0000000000000000 s0 : ffffffd00021bbd0
[ 65.614818] s1 : ffffffd0003bbdf0 a0 : 0000000000000001 a1 : 0000000000000002
[ 65.615237] a2 : ffffffff81618008 a3 : 0000000000000000 a4 : 0000000000000000
[ 65.615637] a5 : ffffffd0003bc000 a6 : 0000000000000002 a7 : ffffffe27d370000
[ 65.616022] s2 : ffffffd0003bbd90 s3 : ffffffff8071a81e s4 : 0000000000003fff
[ 65.616407] s5 : ffffffffffffc000 s6 : 0000000000000000 s7 : ffffffff81618008
[ 65.616845] s8 : 0000000000000001 s9 : 0000000180000040 s10: 0000000000000000
[ 65.617248] s11: 000000000000016b t3 : 000000ff00000000 t4 : 0c6aec92de5e3fd7
[ 65.617672] t5 : fff78f60608fcfff t6 : 0000000000000078
[ 65.618088] status: 0000000000000120 badaddr: ffffffd0003bbde8 cause: 000000000000000d
[ 65.618621] [<ffffffff800048a4>] get_wchan+0x5c/0x88
[ 65.619008] [<ffffffff8022da88>] do_task_stat+0x7a2/0xa46
[ 65.619325] [<ffffffff8022e87e>] proc_tgid_stat+0xe/0x16
[ 65.619637] [<ffffffff80227dd6>] proc_single_show+0x46/0x96
[ 65.619979] [<ffffffff801ccb1e>] seq_read_iter+0x190/0x31e
[ 65.620341] [<ffffffff801ccd70>] seq_read+0xc4/0x104
[ 65.620633] [<ffffffff801a6bfe>] vfs_read+0x6a/0x112
[ 65.620922] [<ffffffff801a701c>] ksys_read+0x54/0xbe
[ 65.621206] [<ffffffff801a7094>] sys_read+0xe/0x16
[ 65.621474] [<ffffffff8000303e>] ret_from_syscall+0x0/0x2
[ 65.622169] ---[ end trace f24856ed2b8789c5 ]---
[ 65.622832] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Signed-off-by: Jisheng Zhang <[email protected]>
---
arch/riscv/kernel/stacktrace.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index ff467b98c3e3..ac7593607fa6 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -132,8 +132,12 @@ unsigned long get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
- if (likely(task && task != current && !task_is_running(task)))
+ if (likely(task && task != current && !task_is_running(task))) {
+ if (!try_get_task_stack(task))
+ return 0;
walk_stackframe(task, NULL, save_wchan, &pc);
+ put_task_stack(task);
+ }
return pc;
}
--
2.32.0
On Thu, 22 Jul 2021 17:22:26 PDT (-0700), [email protected] wrote:
> From: Jisheng Zhang <[email protected]>
>
> Pin the task's stack before calling walk_stackframe() in get_wchan().
> This can fix the panic as reported by Andreas when CONFIG_VMAP_STACK=y:
>
> [ 65.609696] Unable to handle kernel paging request at virtual address ffffffd0003bbde8
> [ 65.610460] Oops [#1]
> [ 65.610626] Modules linked in: virtio_blk virtio_mmio rtc_goldfish btrfs blake2b_generic libcrc32c xor raid6_pq sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua efivarfs
> [ 65.611670] CPU: 2 PID: 1 Comm: systemd Not tainted 5.14.0-rc1-1.g34fe32a-default #1 openSUSE Tumbleweed (unreleased) c62f7109153e5a0897ee58ba52393ad99b070fd2
> [ 65.612334] Hardware name: riscv-virtio,qemu (DT)
> [ 65.613008] epc : get_wchan+0x5c/0x88
> [ 65.613334] ra : get_wchan+0x42/0x88
> [ 65.613625] epc : ffffffff800048a4 ra : ffffffff8000488a sp : ffffffd00021bb90
> [ 65.614008] gp : ffffffff817709f8 tp : ffffffe07fe91b80 t0 : 00000000000001f8
> [ 65.614411] t1 : 0000000000020000 t2 : 0000000000000000 s0 : ffffffd00021bbd0
> [ 65.614818] s1 : ffffffd0003bbdf0 a0 : 0000000000000001 a1 : 0000000000000002
> [ 65.615237] a2 : ffffffff81618008 a3 : 0000000000000000 a4 : 0000000000000000
> [ 65.615637] a5 : ffffffd0003bc000 a6 : 0000000000000002 a7 : ffffffe27d370000
> [ 65.616022] s2 : ffffffd0003bbd90 s3 : ffffffff8071a81e s4 : 0000000000003fff
> [ 65.616407] s5 : ffffffffffffc000 s6 : 0000000000000000 s7 : ffffffff81618008
> [ 65.616845] s8 : 0000000000000001 s9 : 0000000180000040 s10: 0000000000000000
> [ 65.617248] s11: 000000000000016b t3 : 000000ff00000000 t4 : 0c6aec92de5e3fd7
> [ 65.617672] t5 : fff78f60608fcfff t6 : 0000000000000078
> [ 65.618088] status: 0000000000000120 badaddr: ffffffd0003bbde8 cause: 000000000000000d
> [ 65.618621] [<ffffffff800048a4>] get_wchan+0x5c/0x88
> [ 65.619008] [<ffffffff8022da88>] do_task_stat+0x7a2/0xa46
> [ 65.619325] [<ffffffff8022e87e>] proc_tgid_stat+0xe/0x16
> [ 65.619637] [<ffffffff80227dd6>] proc_single_show+0x46/0x96
> [ 65.619979] [<ffffffff801ccb1e>] seq_read_iter+0x190/0x31e
> [ 65.620341] [<ffffffff801ccd70>] seq_read+0xc4/0x104
> [ 65.620633] [<ffffffff801a6bfe>] vfs_read+0x6a/0x112
> [ 65.620922] [<ffffffff801a701c>] ksys_read+0x54/0xbe
> [ 65.621206] [<ffffffff801a7094>] sys_read+0xe/0x16
> [ 65.621474] [<ffffffff8000303e>] ret_from_syscall+0x0/0x2
> [ 65.622169] ---[ end trace f24856ed2b8789c5 ]---
> [ 65.622832] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
> Signed-off-by: Jisheng Zhang <[email protected]>
> ---
> arch/riscv/kernel/stacktrace.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
> index ff467b98c3e3..ac7593607fa6 100644
> --- a/arch/riscv/kernel/stacktrace.c
> +++ b/arch/riscv/kernel/stacktrace.c
> @@ -132,8 +132,12 @@ unsigned long get_wchan(struct task_struct *task)
> {
> unsigned long pc = 0;
>
> - if (likely(task && task != current && !task_is_running(task)))
> + if (likely(task && task != current && !task_is_running(task))) {
> + if (!try_get_task_stack(task))
> + return 0;
> walk_stackframe(task, NULL, save_wchan, &pc);
> + put_task_stack(task);
> + }
> return pc;
> }
Thanks, this is on fixes.