The commit 5054e778fcd9c changed dm-crypt to use compound pages to improve
performance. Unfortunatelly, there was an oversight - normal pages are
accounted in a percpu counter cc->n_allocated_pages and dm-crypt is
limited to allocate at most 2% of memory. Compound pages were not
accounted at all. So, dm-crypt could allocate memory over the limit.
This patch adds the accounting of compound pages, so that memory
consumption of dm-crypt is properly limited.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v6.5
Fixes: 5054e778fcd9c ("dm crypt: allocate compound pages if possible")
---
drivers/md/dm-crypt.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
Index: linux-stable/drivers/md/dm-crypt.c
===================================================================
--- linux-stable.orig/drivers/md/dm-crypt.c 2023-10-31 19:11:25.000000000 +0100
+++ linux-stable/drivers/md/dm-crypt.c 2023-10-31 19:11:46.000000000 +0100
@@ -1700,11 +1700,17 @@ 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--;
}
@@ -1742,10 +1748,13 @@ static void crypt_free_buffer_pages(stru
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);
+ }
}
}
}
