Re: [patch linux-next] userfaultfd: hugetlbfs: unmap the correct pointer

[Dan Carpenter <dan.carpenter@oracle.com>]

On Thu, Jan 12, 2017 at 08:33:27PM +0100, Michal Hocko wrote:
> On Thu 12-01-17 22:20:52, Dan Carpenter wrote:
> > kunmap_atomic() and kunmap() take different pointers.  People often get
> > these mixed up.
> > 
> > Fixes: 16374db2e9a0 ("userfaultfd: hugetlbfs: fix __mcopy_atomic_hugetlb retry/error processing")
> 
> This looks like a linux-next sha1. This is not stable and will change...
> 

Yeah.  But probably Andrew is just going to fold it into the original
anyway.  Probably most of linux-next trees don't rebase so the hash is
good and the people who rebase fold it in so it doesn't show up in the
released code.  It basically never hurts to have the Fixes tag.

> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 6012a05..dfd3604 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -4172,7 +4172,7 @@ long copy_huge_page_from_user(struct page *dst_page,
> >  				(const void __user *)(src + i * PAGE_SIZE),
> >  				PAGE_SIZE);
> >  		if (allow_pagefault)
> > -			kunmap(page_kaddr);
> > +			kunmap(dst_page + 1);
> 
> I guess you meant dst_page + i

Huh.  I would have sworn I copy and pasted this.  Anyway, thanks for
catching this.  I will resend.

regards,
dan carpenter

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