Date: Tue, 16 Oct 2001 11:00:03 -0700 (PDT) From: Jason Evans <jasone@canonware.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/31310: pthread broken with KVA_PAGES=512 Message-ID: <200110161800.f9GI03w02210@freefall.freebsd.org>
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The following reply was made to PR kern/31310; it has been noted by GNATS.
From: Jason Evans <jasone@canonware.com>
To: "justin@skysoft.com.tw" <buggy@kkcity.com.tw>
Cc: FreeBSD-gnats-submit@freebsd.org
Subject: Re: kern/31310: pthread broken with KVA_PAGES=512
Date: Tue, 16 Oct 2001 11:01:39 -0700
On Tue, Oct 16, 2001 at 04:16:51PM +0800, justin@skysoft.com.tw wrote:
>
> >Description:
> KVA_PAGES in kernel config is set to 512, and I had 'make world'
> to update /usr/lib.
>
> When I run any program that use pthread (linked with libc_r),
> it prints:
>
>
> Fatal error 'Cannot allocate red zone for initial thread' at line ? in file
> /usr/src/lib/libc_r/uthread/uthread_init.c (errno = ?)
>
> Abort trap (core dumped)
>
>
> I didn't have this problem on 4.4-RC0 with ldscript.i386 and pmap.h
> patched as the following to enlarge kernel address space to 2G.
I'm not sure I understand what you're doing, so let me try to summarize my
understanding before guessing what the problem is. It sounds like you are
changing the amount of address space reserved for the kernel, which affects
where the userland stack is mapped. Look in
src/lib/libc_r/uthread/uthread_init.c for the mmap() call that creates the
red zone:
/*
* Create a red zone below the main stack. All other stacks are
* constrained to a maximum size by the paramters passed to
* mmap(), but this stack is only limited by resource limits, so
* this stack needs an explicitly mapped red zone to protect the
* thread stack that is just beyond.
*/
if (mmap((void *) USRSTACK - PTHREAD_STACK_INITIAL -
PTHREAD_STACK_GUARD, PTHREAD_STACK_GUARD, 0, MAP_ANON,
-1, 0) == MAP_FAILED)
PANIC("Cannot allocate red zone for initial thread");
The code depends on the USRSTACK macro when determining where to create the
red zone, and I suspect that its value is somewhere in kernel memory in
your case.
From src/sys/i386/include/vmparam.h:
#define VM_MAXUSER_ADDRESS VADDR(UMAXPTDI, UMAXPTEOFF)
#define USRSTACK VM_MAXUSER_ADDRESS
Please let me know if after further diagnostic effort you discover this to
be an actual problem in libc_r.
Jason
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