tree 4926cbaabf26bb0308e9408f280a6cab644331bf
parent 22e4663e916321b72972c69ca0c6b962f529bd78
author Jason Gunthorpe <jgg@nvidia.com> 1605336716 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1605381963 -0800

mm/gup: use unpin_user_pages() in __gup_longterm_locked()

When FOLL_PIN is passed to __get_user_pages() the page list must be put
back using unpin_user_pages() otherwise the page pin reference persists
in a corrupted state.

There are two places in the unwind of __gup_longterm_locked() that put
the pages back without checking.  Normally on error this function would
return the partial page list making this the caller's responsibility,
but in these two cases the caller is not allowed to see these pages at
all.

Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages")
Reported-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/0-v2-3ae7d9d162e2+2a7-gup_cma_fix_jgg@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>