Messages in this thread Patch in this message | | | Date | Tue, 22 Aug 2023 22:14:47 -0700 (PDT) | From | Hugh Dickins <> | Subject | [PATCH mm-hotfixes-unstable] shmem: fix smaps BUG sleeping while atomic |
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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().
Fixes: 230100321518 ("mm/smaps: simplify shmem handling of pte holes") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org # 5.16+ --- mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c index 7a0c1e19d9f8..c512a5e82f8d 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(); -- 2.35.3
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