Date: Tue, 26 Oct 2004 10:30:05 -0700 From: "David O'Brien" <obrien@FreeBSD.org> To: Georgi Guninski <guninski@guninski.com> Cc: freebsd-amd64@FreeBSD.org Subject: Re: two 4GB mallocs => SEGV Message-ID: <20041026173005.GA2984@dragon.nuxi.com> In-Reply-To: <20041026115041.GE2841@sivokote.iziade.m$> References: <20041026115041.GE2841@sivokote.iziade.m$>
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On Tue, Oct 26, 2004 at 02:50:41PM +0300, Georgi Guninski wrote:
> amdkotef64# cat test.c
> #include <stdlib.h>
>
> int main(int ac, char **av)
> {
> char *a, *b;
> size_t siz;
> siz=4L*1024L*1024L*1024L;
> printf("%lx\n",siz);
> a=malloc(siz);
> printf("%lx\n",a);
> b=malloc(siz);
> printf("%lx\n",b);
> }
> amdkotef64# gcc test.c
> amdkotef64# ./a.out
> 100000000
> 503000
> /: write failed, filesystem is full
> Segmentation fault
I don't know why you didn't take this to the next step to try to figure
out what was going on....
# cc -g test.c
# gdb a.out
(gdb) run
Starting program: /var/tmp/a.out
100000000
503000
Program received signal SIGSEGV, Segmentation fault.
0x0000000200503002 in ?? () from /libexec/ld-elf.so.1
(gdb) where
now the output you get isn't but so helpful because you wind up in the
middle of libc. So if you build libc with -g and don't strip the lib
when installing it you get:
(gdb) run
Starting program: /var/tmp/a.out
4294967296
5255168
Program received signal SIGILL, Illegal instruction.
0x0000000200503000 in ?? () from /libexec/ld-elf.so.1
(gdb) where
#0 0x0000000200503000 in ?? () from /libexec/ld-elf.so.1
#1 0x000000020069579d in map_pages (pages=8595189760)
at /usr/src/lib/libc/stdlib/malloc.c:338
#2 0x0000000200695c19 in malloc_pages (size=1048576)
at /usr/src/lib/libc/stdlib/malloc.c:572
#3 0x0000000200695f77 in imalloc (size=4294967296)
at /usr/src/lib/libc/stdlib/malloc.c:740
#4 0x00000002006968ed in pubrealloc (ptr=0x0, size=4294967296,
func=0x2006f8c88 " in malloc():") at /usr/src/lib/libc/stdlib/malloc.c:1128
#5 0x00000002006969d8 in malloc (size=8595189760)
at /usr/src/lib/libc/stdlib/malloc.c:1152
#6 0x00000000004007b4 in main (ac=1, av=0x7fffffffe900) at test.c:11
malloc.c:map_pages() calls brk(2) and this is where it goes to la-la land.
--
-- David (obrien@FreeBSD.org)
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