Re: [PATCH v2] fork: fix oops after fork failure

[Andrew Morton]

On Thu, 23 Aug 2012 19:36:08 +0400
Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:

> When we want to duplicate a new process, dup_task_struct() will undergo
> a series of allocations. If alloc_thread_info_node() fails, we call
> free_task_struct() and return.
> 
> This seems right, but it is not. free_task_struct() will not only free
> the task struct from the kmem_cache, but will also call
> arch_release_task_struct(). The problem is that this function is
> supposed to undo whatever arch-specific work done by
> arch_dup_task_struct(), that is not yet called at this point.  The
> particular problem I ran accross was that in x86, we will arrive at
> fpu_free() without having ever allocated it.

I think ths was already fixed by f19b9f74b7ea3b ("fork: fix error
handling in dup_task()").  As you would have noticed if you were
preparing patches against up-to-date kernel versions!

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