Date: Mon, 23 Jul 2001 12:07:47 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: msmith@freebsd.org, "Eugene L. Vorokov" <vel@bugz.infotecs.ru> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: using syscalls in a module (stack problem ?) Message-ID: <Pine.SOL.4.21.0107231201570.15045-100000@opal> In-Reply-To: <200107231346.f6NDkh403679@bugz.infotecs.ru>
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Just out of curiosity, Linux's kernel stack is one page. Where in the kernel source code that says that we can have two pages instead of one page kernel stack? -Zhihui On Mon, 23 Jul 2001, Eugene L. Vorokov wrote: > > > I call this function with (curproc, PATH_MAX+1), and everything is fine > > > when I have just a few local variables defined in the caller (it all > > > works on MOD_LOAD only). However, if I have 2 buffers, 4096 bytes each, > > > as local variables and then try to allocate userspace memory the same > > > way, kernel crashes - sometimes inside mmap(), sometimes a bit later. > > > > > > Why could this happen ? Is it related to possible stack overflow ? > > > > Yes. The kernel stack is only two pages; you absolutely must not use > > large local variables in the kernel. > > I see. But I still can define them using "static", right ? > > Regards, > Eugene > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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