Re: [PATCH v16 08/11] secretmem: add memcg accounting

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

From: Mike Rapoport rppt@linux.ibm.com

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?