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Re: Silly 100% CPU behavior on a SIG_IGN-ored SIGBUS.

To: Kaz Kylheku <KKylheku@zeugmasystems.com>
Subject: Re: Silly 100% CPU behavior on a SIG_IGN-ored SIGBUS.
From: David Daney <ddaney@caviumnetworks.com>
Date: Tue, 23 Jun 2009 15:03:13 -0700
Cc: linux-mips@linux-mips.org
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Kaz Kylheku wrote:
Hi all,

On kernel 2.6.26, glibc 2.5 (n32), SiByte SB-1 core, the following
program goes into 100% CPU, chewing up about 80% kernel time and
20% user.

#include <stdio.h>
#include <signal.h>

int main(void)
{
  int *deadbeef = (int *) 0xdeadbeef;
  signal(SIGBUS, SIG_IGN);
  printf("*deadbeef == %d\n", *deadbeef);
  return 0;
}

If any fatal exception is ignored, the program should be killed
if that exception happens. 100% CPU is not a useful response.

(If there is a handler, and that handler returns without doing anything
to
prevent a recurrence of the exception when the instruction is re-tried,
that's different).




I wonder if it is another instance of:

http://www.linux-mips.org/git?p=linux.git;a=commitdiff;h=49cf0e2d68dd98dbb28eaca0284e8460ab6ad86d

David Daney

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