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authorJisheng Zhang <jszhang@kernel.org>2021-07-23 03:22:26 +0300
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-07-24 03:29:03 +0300
commit76f5dfacfb42b75e5782c017827877cfcee20474 (patch)
tree1c207942448c8806d386abbaa606ac15615d831f
parentdb6b84a368b495cb7e41be9cb9e73d4d0537d027 (diff)
downloadlinux-76f5dfacfb42b75e5782c017827877cfcee20474.tar.xz
riscv: stacktrace: pin the task's stack in get_wchan
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 <jszhang@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
-rw-r--r--arch/riscv/kernel/stacktrace.c6
1 files changed, 5 insertions, 1 deletions
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;
}