From: Andrew Morton <akpm@zip.com.au>
To: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: free_task_struct() called too early?
Date: Fri, 10 Aug 2001 11:57:51 -0700 [thread overview]
Message-ID: <3B742EAF.8DC816D0@zip.com.au> (raw)
In-Reply-To: <794826DE8867D411BAB8009027AE9EB91011431F@FMSMSX38>
"Chen, Kenneth W" wrote:
>
> When a process terminates, it appears that the task structure is freed too
> early. There are memory references to the kernel task area (task_struct and
> stack space) after free_task_struct(p) is called.
>
> If I modify the following line in include/asm-i386/processor.h
>
> #define free_task_struct(p) free_pages((unsigned long) (p), 1) to
> #define free_task_struct(p) memset((void*) (p), 0xf, PAGE_SIZE*2);
> free_pages((unsigned long) (p), 1)
> then kernel will boot to init and lockup on when first task terminates.
free_pages will not actually free the page if its reference count
is greater than one - you're poisoning the page before it has actually
ceased to be used.
You should zap the page in __free_pages(), after the put_page_testzero()
call has succeeded.
next prev parent reply other threads:[~2001-08-10 18:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-10 18:13 free_task_struct() called too early? Chen, Kenneth W
2001-08-10 18:57 ` Andrew Morton [this message]
[not found] <no.id>
2001-08-10 22:43 ` Alan Cox
2001-08-10 22:57 ` Linus Torvalds
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