lkml.org 
[lkml]   [2020]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [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.

\
 
 \ /
  Last update: 2020-05-22 18:35    [W:0.062 / U:3.336 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site