diff options
| author | Hugh Dickins <hughd@google.com> | 2023-08-22 22:14:47 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-24 14:59:47 -0700 |
| commit | e5548f85b4527c4c803b7eae7887c10bf8f90c97 (patch) | |
| tree | e89cd6f78cdd98fedad9054d38f517249240016c | |
| parent | f84f62e69963d7742acec4340ec1c4c7ef22b887 (diff) | |
shmem: fix smaps BUG sleeping while atomic
smaps_pte_hole_lookup() is calling shmem_partial_swap_usage() with page
table lock held: but shmem_partial_swap_usage() does cond_resched_rcu() if
need_resched(): "BUG: sleeping function called from invalid context".
Since shmem_partial_swap_usage() is designed to count across a range, but
smaps_pte_hole_lookup() only calls it for a single page slot, just break
out of the loop on the last or only page, before checking need_resched().
Link: https://lkml.kernel.org/r/6fe3b3ec-abdf-332f-5c23-6a3b3a3b11a9@google.com
Fixes: 230100321518 ("mm/smaps: simplify shmem handling of pte holes")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org> [5.16+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/shmem.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index f5af4b943e42..d963c747dabc 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -806,14 +806,16 @@ unsigned long shmem_partial_swap_usage(struct address_space *mapping, XA_STATE(xas, &mapping->i_pages, start); struct page *page; unsigned long swapped = 0; + unsigned long max = end - 1; rcu_read_lock(); - xas_for_each(&xas, page, end - 1) { + xas_for_each(&xas, page, max) { if (xas_retry(&xas, page)) continue; if (xa_is_value(page)) swapped++; - + if (xas.xa_index == max) + break; if (need_resched()) { xas_pause(&xas); cond_resched_rcu(); |