dm crypt: account large pages in cc->n_allocated_pages

commit 9793c269da6cd339757de6ba5b2c8681b54c99af upstream.

The commit 5054e778fcd9c ("dm crypt: allocate compound pages if
possible") changed dm-crypt to use compound pages to improve
performance. Unfortunately, there was an oversight: the allocation of
compound pages was not accounted at all. Normal pages are accounted in
a percpu counter cc->n_allocated_pages and dm-crypt is limited to
allocate at most 2% of memory. Because compound pages were not
accounted at all, dm-crypt could allocate memory over the 2% limit.

Fix this by adding the accounting of compound pages, so that memory
consumption of dm-crypt is properly limited.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 5054e778fcd9c ("dm crypt: allocate compound pages if possible")
Cc: stable@vger.kernel.org	# v6.5+
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 5315fd2..cef9353 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1699,11 +1699,17 @@ retry:
                order = min(order, remaining_order);
 
                while (order > 0) {
+                       if (unlikely(percpu_counter_read_positive(&cc->n_allocated_pages) +
+                                       (1 << order) > dm_crypt_pages_per_client))
+                               goto decrease_order;
                        pages = alloc_pages(gfp_mask
                                | __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | __GFP_COMP,
                                order);
-                       if (likely(pages != NULL))
+                       if (likely(pages != NULL)) {
+                               percpu_counter_add(&cc->n_allocated_pages, 1 << order);
                                goto have_pages;
+                       }
+decrease_order:
                        order--;
                }
 
@@ -1741,10 +1747,13 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 
        if (clone->bi_vcnt > 0) { /* bio_for_each_folio_all crashes with an empty bio */
                bio_for_each_folio_all(fi, clone) {
-                       if (folio_test_large(fi.folio))
+                       if (folio_test_large(fi.folio)) {
+                               percpu_counter_sub(&cc->n_allocated_pages,
+                                               1 << folio_order(fi.folio));
                                folio_put(fi.folio);
-                       else
+                       } else {
                                mempool_free(&fi.folio->page, &cc->page_pool);
+                       }
                }
        }
 }