From: Steven Rostedt I hit the check_flags error of lockdep: WARNING: at kernel/lockdep.c:2893 check_flags+0x1a7/0x1d0() [...] hardirqs last enabled at (12567): [] local_bh_enable+0xaa/0x110 hardirqs last disabled at (12569): [] int3+0x16/0x40 softirqs last enabled at (12566): [] lock_sock_nested+0xfb/0x110 softirqs last disabled at (12568): [] tcp_prequeue_process+0x2e/0xa0 The check_flags warning of lockdep tells me that lockdep thought interrupts were disabled, but they were really enabled. The numbers in the above parenthesis show the order of events: 12566: softirqs last enabled: lock_sock_nested 12567: hardirqs last enabled: local_bh_enable 12568: softirqs last disabled: tcp_prequeue_process 12566: hardirqs last disabled: int3 int3 is a breakpoint! Examining this further, I have CONFIG_NET_TCPPROBE enabled which adds break points into the kernel. The paranoid_exit of the return of int3 does not account for enabling interrupts on return to kernel. This code is a bit tricky since it is also used by the nmi handler (when lockdep is off), and we must be careful about the swapgs. We can not call kernel code after the swapgs has been performed. [ Impact: fix lockdep check_flags warning ] Acked-by: Peter Zijlsta Signed-off-by: Steven Rostedt --- arch/x86/kernel/entry_64.S | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1ac9986..987f91f 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1397,7 +1397,10 @@ ENTRY(paranoid_exit) paranoid_swapgs: TRACE_IRQS_IRETQ 0 SWAPGS_UNSAFE_STACK + RESTORE_ALL 8 + jmp irq_return paranoid_restore: + TRACE_IRQS_IRETQ 0 RESTORE_ALL 8 jmp irq_return paranoid_userspace: -- 1.6.2.1 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/