Re: mmap for /proc/vmcore broken since 3.12-rc1

[HATAYAMA Daisuke]

Hello,

(2013/10/08 21:49), Alexey Dobriyan wrote:
> On Mon, Oct 7, 2013 at 5:42 AM, HATAYAMA Daisuke
> <d.hatayama@xxxxxxxxxxxxxx> wrote:
>
> > +static unsigned long
> > +get_unmapped_area_vmcore(struct file *filp, unsigned long addr,
> > +                        unsigned long len, unsigned long pgoff,
> > +                        unsigned long flags)
> > +{
> > +#ifdef CONFIG_MMU
> > +       return current->mm->get_unmapped_area(filp, addr, len, pgoff,
> > flags);
> > +#else
> > +       return -EIO;
> > +#endif
> > +}
> > +
> >   static const struct file_operations proc_vmcore_operations = {
> >          .read           = read_vmcore,
> >          .llseek         = default_llseek,
> >          .mmap           = mmap_vmcore,
> > +       .get_unmapped_area = get_unmapped_area_vmcore,
>
> I think current->mm->get_unmapped_area should be used by core proc code.

What do you actually suggest here? You mean moving this code in proc code?
I don't think you suggest so.

> ENOMEM bug looks unrelated though.

Next step I'll do is to look into vm_unmapped_region() that looks for
for a region fit to a given mmap request and returns its address.
In particular, I'll focus on when vm_unmapped_region() could return
kernel-space address.

--
Thanks.
HATAYAMA, Daisuke

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