From b88d4f1d390a6a232938d27d551f24cf08a2c7e0 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 23 Jun 2006 02:04:20 -0700 Subject: [PATCH] [PATCH] i386: break out of recursion in stackframe walk If CONFIG_FRAME_POINTERS is enabled, and one does a dump_stack() during early SMP init, an infinite stackdump and a bootup hang happens: [] show_trace+0xd/0xf [] dump_stack+0x15/0x17 [] save_trace+0xc3/0xce [] mark_lock+0x8c/0x4fe [] __lockdep_acquire+0x44e/0xaa5 [] lockdep_acquire+0x68/0x84 [] _spin_lock+0x21/0x2f [] prepare_set+0xd/0x5d [] generic_set_all+0x1d/0x201 [] mtrr_ap_init+0x23/0x3b [] identify_cpu+0x2a7/0x2af [] smp_store_cpu_info+0x2f/0xb4 [] start_secondary+0xb5/0x3ec [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [] end_of_stack_stop_unwind_function+0x1/0x4 [...] Due to "end_of_stack_stop_unwind_function" recursing back to itself in the EBP stackframe-walker. So avoid this type of recursion when walking the stack . Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/traps.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index 0e498369f3..df9d210626 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -149,6 +149,12 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo, while (valid_stack_ptr(tinfo, (void *)ebp)) { addr = *(unsigned long *)(ebp + 4); printed = print_addr_and_symbol(addr, log_lvl, printed); + /* + * break out of recursive entries (such as + * end_of_stack_stop_unwind_function): + */ + if (ebp == *(unsigned long *)ebp) + break; ebp = *(unsigned long *)ebp; } #else -- 2.39.5