From 0d2b8579add41e08aa1110da864f1071d58e6048 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 26 Oct 2016 10:41:50 -0500 Subject: [PATCH] x86/dumpstack: Warn on stack recursion Print a warning if stack recursion is detected. Use printk_deferred_once() because the unwinder can be called with the console lock by lockdep via save_stack_trace(). Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/def18247aafaab480844484398e793f552b79bda.1477496147.git.jpoimboe@redhat.com [ Unbroke the lines. ] Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack_32.c | 4 +++- arch/x86/kernel/dumpstack_64.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index 90cf460..d7d20999 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -109,8 +109,10 @@ recursion_check: * just break out and report an unknown stack type. */ if (visit_mask) { - if (*visit_mask & (1UL << info->type)) + if (*visit_mask & (1UL << info->type)) { + printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type); goto unknown; + } *visit_mask |= 1UL << info->type; } diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 310abf4..ab0f8b9 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -128,8 +128,10 @@ recursion_check: * just break out and report an unknown stack type. */ if (visit_mask) { - if (*visit_mask & (1UL << info->type)) + if (*visit_mask & (1UL << info->type)) { + printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type); goto unknown; + } *visit_mask |= 1UL << info->type; } -- 2.7.4