diff mbox series

[06/14] mm/gup: use unpin_user_pages() in __gup_longterm_locked()

Message ID 20201114065156.AkB0cZWK4%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [01/14] mm/compaction: count pages and stop correctly during page isolation | expand

Commit Message

Andrew Morton Nov. 14, 2020, 6:51 a.m. UTC 
From: Jason Gunthorpe <jgg@nvidia.com>
Subject: 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.

Link: https://lkml.kernel.org/r/0-v2-3ae7d9d162e2+2a7-gup_cma_fix_jgg@nvidia.com
Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reported-by: Ira Weiny <ira.weiny@intel.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)
diff mbox series

Patch

--- a/mm/gup.c~mm-gup-use-unpin_user_pages-in-__gup_longterm_locked
+++ a/mm/gup.c
@@ -1647,8 +1647,11 @@  check_again:
 		/*
 		 * 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
 			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;
 		}