Date: Tue, 26 Oct 2004 14:32:27 -0700 From: "David O'Brien" <obrien@freebsd.org> To: "James R. Van Artsalen" <james@jrv.org> Cc: freebsd-amd64@freebsd.org Subject: Re: two 4GB mallocs => SEGV Message-ID: <20041026213227.GA95016@dragon.nuxi.com> In-Reply-To: <417E8F7A.70009@jrv.org> References: <20041026115041.GE2841@sivokote.iziade.m$> <20041026173005.GA2984@dragon.nuxi.com> <417E8F7A.70009@jrv.org>
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On Tue, Oct 26, 2004 at 12:55:06PM -0500, James R. Van Artsalen wrote:
> David O'Brien wrote:
>
> >malloc.c:map_pages() calls brk(2) and this is where it goes to la-la land.
> >
> >
> >
> The brk() kernel call is probably failing due to ulimit being exceeded
> and not anything mysterious.
# ulimit -a | grep virt
virtual memory (kbytes, -v) unlimited
BTW, a statically built binary (ie, using libc.a) just hangs in the
brk(2) call.
> A few months ago I posted this bug in the libc brk(2) code - the stack
> is not balanced if the kernel returns an error. I'm not running current
> code at the moment but see if you brk.S has a stack issue at the err:
> label. Stick in this pop if so and report if malloc(3c) then returns
> NULL instead of crashing, then up your ulimit and try again and see if
> all works without error.
>
> --- lib/libc/amd64/sys/brk.S.~1~ Sat May 24 12:35:23 2003
> +++ lib/libc/amd64/sys/brk.S Fri Apr 9 02:02:22 2004
> @@ -78,6 +78,7 @@
> popq %rdi
> ret
> err:
> + popq %rdi
> #ifdef PIC
> movq PIC_GOT(HIDENAME(cerror)),%rdx
> jmp *%rdx
Today's code has:
err:
addq $8, %rsp
#ifdef PIC
movq PIC_GOT(HIDENAME(cerror)),%rdx
jmp *%rdx
so the stack should be OK.
--
-- David (obrien@FreeBSD.org)
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