The patch titled
Subject: mm/gup: use unpin_user_pages() in __gup_longterm_locked()
has been added to the -mm tree. Its filename is
mm-gup-use-unpin_user_pages-in-__gup_longterm_locked.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-use-unpin_user_pages-in-__gup_longterm_locked.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-use-unpin_user_pages-in-__gup_longterm_locked.patch
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------------------------------------------------------
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
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@xxxxxxxxxx
Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages")
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reported-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- 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;
}
_
Patches currently in -mm which might be from jgg@xxxxxxxxxx are
mm-gup-use-unpin_user_pages-in-__gup_longterm_locked.patch
