On Thu, Apr 19, 2001 at 11:05:03AM -0500, Victor Zandy wrote:
>
> We have found that one of our programs can cause system-wide
> corruption of the x86 FPU under 2.2.16 and 2.2.17.
....
>
> We see this problem on dual 550MHz Xeons with 1GB RAM.
Hm, I started to wonder if this is not somewhat related to a recent
report I got. "The victim" was running 2.2.19 (basically) on an SMP
Alpha UP2000+ with two 800 MHz processors. He managed to reduce the
problem to a rather small test case and I attach sources, Makefile and
a "loop.sh" driver as a shar archive if you want to have a closer look.
This "loop.sh" simply fires triplets of "harry" process in a loop.
The guy hit by this gets apparently random floating point exceptions
starting with roughly sixth process and later intervals between bombs
will vary. I have also 'strace' outputs from failing processes but
they are not telling very much. 'gdb' is also not very illuminating:
Program received signal SIGFPE, Arithmetic exception.
0x1200010a8 in vadd_ (a=0x11fff21e4, ia=0x120003294, b=0x11fff7004,
ib=0x120003294, c=0x11fffbe20, ic=0x120003294, n=0x11ffffc70) at vadd.f:99
99 C(CI) = A(AI) + B(BI)
Current language: auto; currently fortran
(gdb) p *ia
$10 = 1
(gdb) p *ib
$11 = 1
(gdb) p *ic
$12 = 1
(gdb) p *n
Cannot access memory at address 0x4
(gdb) p *(0x11ffffc70)
$13 = 1024
(gdb) info locals
n = (PTR TO -> ( integer )) 0x4
__g77_expr_0 = 10
He tells me that he is getting that on two different machines he has
around.
The trouble is that I tried to repeat that with different hardware,
kernels, compilers and libraries and I failed even on SMP; but I got an
access to a box with only 667 MHz processors. OTOH he is running
right now 2.4.3-ac9 plus Andrea Arcangeli patches for rw semaphores
on Alpha and he reports that the problem went away (and, hopefuly,
nothing else will crop out :-).
Anybody can offer an insight what that may really be? It may be,
of course, totally unrelated to this report from Victor Zandy.
Michal
michal@harddata.com
--ibTvN161/egqYuK8
Content-Type: application/x-shar
Content-Disposition: attachment; filename="fpbomb.shar"
#!/bin/sh
# This is a shell archive (produced by GNU sharutils 4.2).
# To extract the files from this archive, save it to some FILE, remove
# everything before the `!/bin/sh' line above, then type `sh FILE'.
#
# Made on 2001-04-19 13:48 MDT by <michal@mail>.
# Source directory was `/home/michal/broi'.
#
# Existing files will *not* be overwritten unless `-c' is specified.
#
# This shar contains:
# length mode name
# ------ ---------- ------------------------------------------
# 117 -rw-rw-r-- Makefile
# 288 -rw-rw-r-- harry.f
# 3209 -rw-rw-r-- vadd.f
# 2829 -rw-rw-r-- vmov.f
# 69 -rwxrwxr-x loop.sh
#
save_IFS="${IFS}"
IFS="${IFS}:"
gettext_dir=FAILED
locale_dir=FAILED
first_param="$1"
for dir in $PATH
do
if test "$gettext_dir" = FAILED && test -f $dir/gettext \
&& ($dir/gettext --version >/dev/null 2>&1)
then
set `$dir/gettext --version 2>&1`
if test "$3" = GNU
then
gettext_dir=$dir
fi
fi
if test "$locale_dir" = FAILED && test -f $dir/shar \
&& ($dir/shar --print-text-domain-dir >/dev/null 2>&1)
then
locale_dir=`$dir/shar --print-text-domain-dir`
fi
done
IFS="$save_IFS"
if test "$locale_dir" = FAILED || test "$gettext_dir" = FAILED
then
echo=echo
else
TEXTDOMAINDIR=$locale_dir
export TEXTDOMAINDIR
TEXTDOMAIN=sharutils
export TEXTDOMAIN
echo="$gettext_dir/gettext -s"
fi
touch -am 1231235999 $$.touch >/dev/null 2>&1
if test ! -f 1231235999 && test -f $$.touch; then
shar_touch=touch
else
shar_touch=:
echo
$echo 'WARNING: not restoring timestamps. Consider getting and'
$echo "installing GNU \`touch', distributed in GNU File Utilities..."
echo
fi
rm -f 1231235999 $$.touch
#
if mkdir _sh26171; then
$echo 'x -' 'creating lock directory'
else
$echo 'failed to create lock directory'
exit 1
fi
# ============= Makefile ==============
if test -f 'Makefile' && test "$first_param" != -c; then
$echo 'x -' SKIPPING 'Makefile' '(file already exists)'
else
$echo 'x -' extracting 'Makefile' '(text)'
sed 's/^X//' << 'SHAR_EOF' > 'Makefile' &&
FC=g77
FFLAGS=-O2
X
harry: harry.o vmov.o vadd.o
X $(FC) -v -o harry harry.o vmov.o vadd.o
X
clean:
X rm -rf harry *.o
X
X
SHAR_EOF
$shar_touch -am 04111758101 'Makefile' &&
chmod 0664 'Makefile' ||
$echo 'restore of' 'Makefile' 'failed'
if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
&& ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
md5sum -c << SHAR_EOF >/dev/null 2>&1 \
|| $echo 'Makefile:' 'MD5 check failed'
c211b540542140580404c93197c51381 Makefile
SHAR_EOF
else
shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'Makefile'`"
test 117 -eq "$shar_count" ||
$echo 'Makefile:' 'original size' '117,' 'current size' "$shar_count!"
fi
fi
# ============= harry.f ==============
if test -f 'harry.f' && test "$first_param" != -c; then
$echo 'x -' SKIPPING 'harry.f' '(file already exists)'
else
$echo 'x -' extracting 'harry.f' '(text)'
sed 's/^X//' << 'SHAR_EOF' > 'harry.f' &&
X
C TMATH
X
X REAL A(5000), B(5000),C(5000)
X
X NTIME=50000
X N=1024
X TMAX=1000.0
X TEMP=0.0
X NZERO=0
X
X DO I=1,5000
X A(I)=sin(TEMP)
X B(I)=REAL(I)*0.9
X TEMP=TEMP+0.2
X ENDDO
X
X DO J=1,NTIME
X CALL VMOV(a,1,C,1,N)
X ENDDO
X
X DO J=1,NTIME
X CALL VADD(a,1,b,1,C,1,N)
X ENDDO
X
X
X call exit(1)
X end
SHAR_EOF
$shar_touch -am 04111113101 'harry.f' &&
chmod 0664 'harry.f' ||
$echo 'restore of' 'harry.f' 'failed'
if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
&& ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
md5sum -c << SHAR_EOF >/dev/null 2>&1 \
|| $echo 'harry.f:' 'MD5 check failed'
4916022df127194190f21283288bba26 harry.f
SHAR_EOF
else
shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'harry.f'`"
test 288 -eq "$shar_count" ||
$echo 'harry.f:' 'original size' '288,' 'current size' "$shar_count!"
fi
fi
# ============= vadd.f ==============
if test -f 'vadd.f' && test "$first_param" != -c; then
$echo 'x -' SKIPPING 'vadd.f' '(file already exists)'
else
$echo 'x -' extracting 'vadd.f' '(text)'
sed 's/^X//' << 'SHAR_EOF' > 'vadd.f' &&
C****** @(#)VADD 5.1 10/11/89 Copyright (c) 1989 by FPS Computing
C
C Copyright (c) 1989 by FPS Computing
C
C Permission to use, copy, modify, and distribute this software,
C FPSMath (TM), and its documentation for any purpose and without fee
C is hereby granted, provided that the above copyright notice and this
C permission notice appear in all copies of this software and its
C supporting documentation, and that FPS Computing and FPSMath (TM) be
C mentioned in all documentation and advertisement of any products
C derived from or using this software. This software library may not
C be renamed in any way and must be called FPSMath (TM). FPS Computing
C makes no representations about the suitability of this software for
C any purpose. It is provided AS IS without express or implied
C warranty including any WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE
C AND MERCHANTABILITY. The information contained in FPSMath (TM) is
C subject to change without notice.
C
C FPSMath and FPS Computing are Trademarks of Floating Point Systems,
C Inc.
C
C-----------------------------------------------------------------------
C
C V E C T O R A D D
C
C PURPOSE:
C To add the elements of two vectors.
C
C FORTRAN SYNOPSIS:
C SUBROUTINE VADD (A, IA, B, IB, C, IC, N)
C REAL*4 A(1), B(1), C(1)
C INTEGER*4 IA, IB, IC, N
C
C INPUT PARAMETERS:
C A Real Vector
C Input vector.
C IA Integer Scalar
C Element stride for A.
C B Real Vector
C Input vector.
C IB Integer Scalar
C Element stride for B.
C IC Integer Scalar
C Element stride for C.
C N Integer Scalar
C Element count.
C
C OUTPUT PARAMETERS:
C C Real Vector
C Output vector.
C
C DESCRIPTION:
C C(m) = B(m) + A(m); for m = 1 to N
C
C EXAMPLE:
C Input:
C
C N = 3
C IA = 1
C IB = 1
C IC = 1
C
C A: 0.0 1.0 2.0
C B: 1.0 2.0 3.0
C
C Output:
C
C C: 1.0 3.0 5.0
C
C-----------------------------------------------------------------------
C
X SUBROUTINE VADD (A, IA, B, IB, C, IC, N)
C
X REAL*4 A(1), B(1), C(1)
X INTEGER*4 IA, IB, IC, N
C
C----------------------------------------------------------------------
C
X INTEGER*4 AI
C Pointer to A vector
X INTEGER*4 BI
C Pointer to B vector
X INTEGER*4 CI
C Pointer to C vector
X INTEGER*4 I
C Index for DO loop
C
C----------------------------------------------------------------------
C
C Verify parameter
C
X IF (N .LE. 0) GOTO 9999
C
X AI = 1
X BI = 1
X CI = 1
C
X DO 10 I = 1, N
X C(CI) = A(AI) + B(BI)
X AI = AI + IA
X BI = BI + IB
X CI = CI + IC
X 10 CONTINUE
C
X 9999 CONTINUE
X RETURN
X END
SHAR_EOF
$shar_touch -am 04111113101 'vadd.f' &&
chmod 0664 'vadd.f' ||
$echo 'restore of' 'vadd.f' 'failed'
if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
&& ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
md5sum -c << SHAR_EOF >/dev/null 2>&1 \
|| $echo 'vadd.f:' 'MD5 check failed'
30b99c91c250dd3ef848f627f3d2cb6e vadd.f
SHAR_EOF
else
shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'vadd.f'`"
test 3209 -eq "$shar_count" ||
$echo 'vadd.f:' 'original size' '3209,' 'current size' "$shar_count!"
fi
fi
# ============= vmov.f ==============
if test -f 'vmov.f' && test "$first_param" != -c; then
$echo 'x -' SKIPPING 'vmov.f' '(file already exists)'
else
$echo 'x -' extracting 'vmov.f' '(text)'
sed 's/^X//' << 'SHAR_EOF' > 'vmov.f' &&
C****** @(#)VMOV 5.1 10/11/89 Copyright (c) 1989 by FPS Computing
C
C Copyright (c) 1989 by FPS Computing
C
C Permission to use, copy, modify, and distribute this software,
C FPSMath (TM), and its documentation for any purpose and without fee
C is hereby granted, provided that the above copyright notice and this
C permission notice appear in all copies of this software and its
C supporting documentation, and that FPS Computing and FPSMath (TM) be
C mentioned in all documentation and advertisement of any products
C derived from or using this software. This software library may not
C be renamed in any way and must be called FPSMath (TM). FPS Computing
C makes no representations about the suitability of this software for
C any purpose. It is provided AS IS without express or implied
C warranty including any WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE
C AND MERCHANTABILITY. The information contained in FPSMath (TM) is
C subject to change without notice.
C
C FPSMath and FPS Computing are Trademarks of Floating Point Systems,
C Inc.
C
C-----------------------------------------------------------------------
C
C V E C T O R M O V E
C
C PURPOSE:
C To move elements from one vector to another.
C
C FORTRAN SYNOPSIS:
C SUBROUTINE VMOV (A, IA, C, IC, N)
C REAL*4 A(1), C(1)
C INTEGER*4 IA, IC, N
C
C INPUT PARAMETERS:
C A Real Vector
C Input vector.
C IA Integer Scalar
C Element stride for A.
C IC Integer Scalar
C Element stride for C.
C N Integer Scalar
C Element count.
C
C OUTPUT PARAMETERS:
C C Real Vector
C Output vector.
C
C DESCRIPTION:
C C(m) = A(m); for m = 1 to N
C
C EXAMPLE:
C Input:
C
C N = 3
C IA = 1
C IC = 1
C
C A: 0.0 1.0 2.0
C
C Output:
C
C C: 0.0 1.0 2.0
C
C----------------------------------------------------------------------
C
X SUBROUTINE VMOV(A, IA, C, IC, N)
C
X REAL*4 A(1), C(1)
X INTEGER*4 IA, IC, N
C
C----------------------------------------------------------------------
C
X INTEGER*4 AI
C Pointer to A vector
X INTEGER*4 CI
C Pointer to C vector
X INTEGER*4 I
C Index for DO loop
C
C----------------------------------------------------------------------
C
C Verify parameter
C
X IF (N .LE. 0) GOTO 9999
C
X AI = 1
X CI = 1
C
X DO 10 I = 1, N
X C(CI) = A(AI)
X AI = AI + IA
X CI = CI + IC
X 10 CONTINUE
C
X 9999 CONTINUE
X RETURN
X END
SHAR_EOF
$shar_touch -am 04111113101 'vmov.f' &&
chmod 0664 'vmov.f' ||
$echo 'restore of' 'vmov.f' 'failed'
if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
&& ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
md5sum -c << SHAR_EOF >/dev/null 2>&1 \
|| $echo 'vmov.f:' 'MD5 check failed'
4948aa1db01ce8e130b0417787feb22d vmov.f
SHAR_EOF
else
shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'vmov.f'`"
test 2829 -eq "$shar_count" ||
$echo 'vmov.f:' 'original size' '2829,' 'current size' "$shar_count!"
fi
fi
# ============= loop.sh ==============
if test -f 'loop.sh' && test "$first_param" != -c; then
$echo 'x -' SKIPPING 'loop.sh' '(file already exists)'
else
$echo 'x -' extracting 'loop.sh' '(text)'
sed 's/^X//' << 'SHAR_EOF' > 'loop.sh' &&
#!/bin/sh
X
while : ; do
X ./harry &
X ./harry &
X ./harry
done
SHAR_EOF
$shar_touch -am 04111759101 'loop.sh' &&
chmod 0775 'loop.sh' ||
$echo 'restore of' 'loop.sh' 'failed'
if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
&& ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
md5sum -c << SHAR_EOF >/dev/null 2>&1 \
|| $echo 'loop.sh:' 'MD5 check failed'
1120d720e9bf809b9972eaced9030d7b loop.sh
SHAR_EOF
else
shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'loop.sh'`"
test 69 -eq "$shar_count" ||
$echo 'loop.sh:' 'original size' '69,' 'current size' "$shar_count!"
fi
fi
rm -fr _sh26171
exit 0
--ibTvN161/egqYuK8--
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