[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:
[<c0104e7f>] show_trace+0xd/0xf
[<c0104e96>] dump_stack+0x15/0x17
[<c01440df>] save_trace+0xc3/0xce
[<c014527d>] mark_lock+0x8c/0x4fe
[<c0145df5>] __lockdep_acquire+0x44e/0xaa5
[<c0146798>] lockdep_acquire+0x68/0x84
[<c1048699>] _spin_lock+0x21/0x2f
[<c010d918>] prepare_set+0xd/0x5d
[<c010daa8>] generic_set_all+0x1d/0x201
[<c010ca9a>] mtrr_ap_init+0x23/0x3b
[<c010ada8>] identify_cpu+0x2a7/0x2af
[<c01192a7>] smp_store_cpu_info+0x2f/0xb4
[<c01197d0>] start_secondary+0xb5/0x3ec
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] end_of_stack_stop_unwind_function+0x1/0x4
[<c104ec11>] 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 <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 0e49836..df9d210 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -149,6 +149,12 @@
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