[PATCH v3 03/10] x86/dumpstack: fix occasionally missing registers

[Josh Poimboeuf]

If two consecutive stack frames have pt_regs, the oops dump code fails
to print the second frame's registers.  Fix that.

Fixes: 3b3fa11bc700 ("x86/dumpstack: Print any pt_regs found on the stack")
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 arch/x86/kernel/dumpstack.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index dbce3cc..bd265a4 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -94,6 +94,9 @@ void show_trace_log_lvl(struct task_struct *task, struct 
pt_regs *regs,
                if (stack_name)
                        printk("%s <%s>\n", log_lvl, stack_name);
 
+               if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
+                       __show_regs(regs, 0);
+
                /*
                 * Scan the stack, printing any text addresses we find.  At the
                 * same time, follow proper stack frames with the unwinder.
@@ -118,10 +121,8 @@ void show_trace_log_lvl(struct task_struct *task, struct 
pt_regs *regs,
                         * Don't print regs->ip again if it was already printed
                         * by __show_regs() below.
                         */
-                       if (regs && stack == &regs->ip) {
-                               unwind_next_frame(&state);
-                               continue;
-                       }
+                       if (regs && stack == &regs->ip)
+                               goto next;
 
                        if (stack == ret_addr_p)
                                reliable = 1;
@@ -144,6 +145,7 @@ void show_trace_log_lvl(struct task_struct *task, struct 
pt_regs *regs,
                        if (!reliable)
                                continue;
 
+next:
                        /*
                         * Get the next frame from the unwinder.  No need to
                         * check for an error: if anything goes wrong, the rest
@@ -153,7 +155,7 @@ void show_trace_log_lvl(struct task_struct *task, struct 
pt_regs *regs,
 
                        /* if the frame has entry regs, print them */
                        regs = unwind_get_entry_regs(&state);
-                       if (regs)
+                       if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
                                __show_regs(regs, 0);
                }
 
-- 
2.7.5