The patch titled
Subject: mm/gup.c: allow CMA migration to propagate errors back to caller
has been added to the -mm tree. Its filename is
mm-gup-allow-cma-migration-to-propagate-errors-back-to-caller.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-allow-cma-migration-to-propagate-errors-back-to-caller.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-allow-cma-migration-to-propagate-errors-back-to-caller.patch
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------------------------------------------------------
From: zhong jiang <zhongjiang@xxxxxxxxxx>
Subject: mm/gup.c: allow CMA migration to propagate errors back to caller
check_and_migrate_cma_pages() was recording the result of
__get_user_pages_locked() in an unsigned "nr_pages" variable. Because
__get_user_pages_locked() returns a signed value that can include negative
errno values, this had the effect of hiding errors.
Change check_and_migrate_cma_pages() implementation so that it uses a
signed variable instead, and propagates the results back to the caller
just as other gup internal functions do.
This was discovered with the help of unsigned_lesser_than_zero.cocci.
Link: http://lkml.kernel.org/r/1571671030-58029-1-git-send-email-zhongjiang@xxxxxxxxxx
Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx>
Suggested-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/mm/gup.c~mm-gup-allow-cma-migration-to-propagate-errors-back-to-caller
+++ a/mm/gup.c
@@ -1443,6 +1443,7 @@ static long check_and_migrate_cma_pages(
bool drain_allow = true;
bool migrate_allow = true;
LIST_HEAD(cma_page_list);
+ long ret = nr_pages;
check_again:
for (i = 0; i < nr_pages;) {
@@ -1504,17 +1505,18 @@ check_again:
* again migrating any new CMA pages which we failed to isolate
* earlier.
*/
- nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages,
+ ret = __get_user_pages_locked(tsk, mm, start, nr_pages,
pages, vmas, NULL,
gup_flags);
- if ((nr_pages > 0) && migrate_allow) {
+ if ((ret > 0) && migrate_allow) {
+ nr_pages = ret;
drain_allow = true;
goto check_again;
}
}
- return nr_pages;
+ return ret;
}
#else
static long check_and_migrate_cma_pages(struct task_struct *tsk,
_
Patches currently in -mm which might be from zhongjiang@xxxxxxxxxx are
mm-gup-allow-cma-migration-to-propagate-errors-back-to-caller.patch
