Messages in this thread | | | Date | Fri, 22 May 2020 18:35:04 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 2/2] locking/spinlock/debug: Add checks for kgdb trap safety |
| |
On Fri, May 22, 2020 at 03:55:10PM +0100, Daniel Thompson wrote: > In general it is not safe to call spin_lock() whilst executing in the > kgdb trap handler. The trap can be entered from all sorts of execution > context (NMI, IRQ, irqs disabled, etc) and the kgdb/kdb needs to be > as resillient as possible. > > Currently it is difficult to spot mistakes in the kgdb/kdb logic > (especially so for kdb because it uses more kernel features than > pure-kgdb). Let's provide a means to bring attention to deadlock > risks in the debug code.
I really dislike this thing. Also, commit:
f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions")
should be able to trigger here when the kgdb traps are marked as NMI. x86 will soon have that.
| |