Re: [9fans] Race condition in /sys/src/9/pc/trap.c?

you can get similar effects by remapping things.
i meant that it isn't likely to happen by accident, so am i bovvered?
fault386 needs to be fixed mainly by or for people running a shared cpu
server with hostile users (ie, students).
for the rest of us it might be more useful to have the panic
to prevent real kernel bugs (ie, just bad pointers in device driver implementations)
from postnoting a process instead of stopping the system.
having said that, it could be argued that even in that case
a postnote to the invoking process would allow the rest of the system
to run and `might not' mean that the broken driver has wrecked other
data structures outside it in kernel memory.
--- Begin Message ---
it ensures mmuflushes in all other processes (sharing that segment) as well.
in fact, the crash you describe just emphasises that point:
the page reference no longer exists, hence the fault.

the problem (which frankly doesn't bother me) is that fault386
is being overly cautious in assuming that a page fault that occurs
in system mode but can't map a page successfully is necessarily a kernel bug:
that's not true. it could just note the process instead.
(it doesn't bother me because since unix days i've seen less than a handful
of programs that SHRINK their existing data segments, and i think that's the
only case that can cause the panic you're seeing.)

if this case is really not important, would it make sense
to disallow shrinking segments? it might be worth it just
to be able to define Eshrinkage.

- erik
--- End Message ---

Relevant Pages

  • Re: [9fans] Race condition in /sys/src/9/pc/trap.c?
    ... the page reference no longer exists, hence the fault. ... (it doesn't bother me because since unix days i've seen less than a handful ... to disallow shrinking segments? ...
    (comp.os.plan9)
  • Re: [RFC/SERIOUS] grilling troubled CPUs for fun and profit?
    ... information about the double fault if we're about to reset faster than ... I don't know why you go to the bother of installing such a handler. ... No release of Red Hat Linux ever shipped with a double fault hander. ... Upon fan failure, I once had an athlon MP *completely shatter* ...
    (Linux-Kernel)
  • Re: Bowing
    ... Kirk Lawson wrote: ... Why bother. ... It's not like you are going to get any sleep for the next 6 months. ... night but it *wasn't* my daughter's fault. ...
    (rec.martial-arts)
  • Re: Crane crash mans inquest opens
    ... to get a grudging admission that maybe the motorist was at fault. ... and if you bothered actually _reading_ a few posts ... clear he doesn't even read things he directly asks for so why bother) ...
    (uk.transport)
  • Re: spam filter
    ... > How is it Outlook's fault that you don't bother to upgrade to the latest ... > the Yahoo Plus mail options to disable "Include Bulk Mail folder when ...
    (microsoft.public.outlook.general)
Loading