Messages in this thread | | | Date | Wed, 10 Jun 2020 17:41:40 +0100 | From | Daniel Thompson <> | Subject | Re: [PATCH] printk/kdb: Redirect printk messages into kdb in any context |
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On Sat, May 16, 2020 at 01:36:38AM +0900, Sergey Senozhatsky wrote: > On (20/05/15 17:32), Sumit Garg wrote: > > > Can I please have some context what problem does this solve? > > > > You can find the problem description here [1] which leads to this fix. > > [..] > > > [1] https://lkml.org/lkml/2020/5/12/213 > > Thanks for the link. I'm slightly surprised it took so many years > to notice the addition of printk_nmi/printk_safe :)
Rather by coincidence (at least I think its a coincidence) the problem has recently become much more obvious.
0d00449c7a28 ("x86: Replace ist_enter() with nmi_enter()") just brought this to the surface by treating debug traps as NMIs. This means the CPU that takes a breakpoint, and where almost all of the kdb printk() calls take place, will now unconditionally have printk() interception enabled.
Daniel.
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