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

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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: 3faa52c03f ("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>
This commit is contained in:
Jason Gunthorpe 2020-11-13 22:51:56 -08:00 committed by Linus Torvalds
parent 22e4663e91
commit 96e1fac162
1 changed files with 10 additions and 4 deletions
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14
mm/gup.c
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@ -1647,8 +1647,11 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
/*
* drop the above get_user_pages reference.
*/
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
if (gup_flags & FOLL_PIN)
unpin_user_pages(pages, nr_pages);
else
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
(unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
@ -1728,8 +1731,11 @@ static long __gup_longterm_locked(struct mm_struct *mm,
goto out;
if (check_dax_vmas(vmas_tmp, rc)) {
for (i = 0; i < rc; i++)
put_page(pages[i]);
if (gup_flags & FOLL_PIN)
unpin_user_pages(pages, rc);
else
for (i = 0; i < rc; i++)
put_page(pages[i]);
rc = -EOPNOTSUPP;
goto out;
}