On Thu 21-01-21 14:27:20, Mike Rapoport wrote:

From: Mike Rapoport <redacted>

Account memory consumed by secretmem to memcg. The accounting is updated
when the memory is actually allocated and freed.

What does this mean? What are the lifetime rules?

[...]

+static int secretmem_account_pages(struct page *page, gfp_t gfp, int order)
+{
+	int err;
+
+	err = memcg_kmem_charge_page(page, gfp, order);
+	if (err)
+		return err;
+
+	/*
+	 * seceremem caches are unreclaimable kernel allocations, so treat
+	 * them as unreclaimable slab memory for VM statistics purposes
+	 */
+	mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B,
+			      PAGE_SIZE << order);

A lot of memcg accounted memory is not reclaimable. Why do you abuse
SLAB counter when this is not a slab owned memory? Why do you use the
kmem accounting API when __GFP_ACCOUNT should give you the same without
this details?
-- 
Michal Hocko
SUSE Labs