Re: kern/44402: page fault in supervisor mode in netbsd:filt_piperead

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR kern/44402; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/44402: page fault in supervisor mode in netbsd:filt_piperead
Date: Mon, 31 Jan 2011 05:21:02 +0000

 On Mon, Jan 17, 2011 at 10:15:06PM +0000, Krister Walfridsson wrote:
  >  The faulting address netbsd:filt_piperead+0xf3 correspond to 
  >  kern/sys_pipe.c:1404 which is the line "mutex_exit(rpipe->pipe_lock);" in
  >  
  >           if ((hint & NOTE_SUBMIT) == 0) {
  >                   mutex_exit(rpipe->pipe_lock);
  >           }
 
 That doesn't make any sense... :(
 
  >  Setting ddb.commandonenter to "trace" just loops the same info:
  >  
  >  filt_piperead(cef5a600,0,cef59cac,c04854b6,cef59c88,cef5a9b4,2,2,0,2) at 
  >  netbsd:filt_piperead+0xf3
  >  uvm_fault(0xceb59ba0, 0, 1) -> 0xe
  >  fatal page fault in supervisor mode
  >  trap type 6 code 0 eip c024e2a0 cs 8 eflags 10246 cr2 249 ilevel 8
  >  kernel: supervisor trap page fault, code=0
  >  Faulted in DDB; continuing...
 
 Blah. I guess the stack's been garbaged and it's dying on rpipe
 because rpipe is a local... 
 
 How repeatable is it?
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost