Re: [PATCH v2] memcg: add per-memcg vmalloc stat
From: Michal Hocko <mhocko@suse.com>
Date: 2021-12-27 10:48:40
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On Tue 21-12-21 21:24:57, Shakeel Butt wrote:
The kvmalloc* allocation functions can fallback to vmalloc allocations and more often on long running machines. In addition the kernel does have __GFP_ACCOUNT kvmalloc* calls. So, often on long running machines, the memory.stat does not tell the complete picture which type of memory is charged to the memcg. So add a per-memcg vmalloc stat. Signed-off-by: Shakeel Butt <redacted>
The counter is useful IMHO. I just have one implementation specific question. [...]
quoted hunk ↗ jump to hunk
@@ -2626,6 +2627,9 @@ static void __vunmap(const void *addr, int deallocate_pages) unsigned int page_order = vm_area_page_order(area); int i; + mod_memcg_page_state(area->pages[0], MEMCG_VMALLOC, + -(int)area->nr_pages); + for (i = 0; i < area->nr_pages; i += 1U << page_order) { struct page *page = area->pages[i];@@ -2964,6 +2968,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, page_order, nr_small_pages, area->pages); atomic_long_add(area->nr_pages, &nr_vmalloc_pages); + mod_memcg_page_state(area->pages[0], MEMCG_VMALLOC, area->nr_pages); /* * If not enough pages were obtained to accomplish an
Is it safe to assume that the whole area is always charged to the same memcg? I am not really deeply familiar with vmalloc internals but is it possible that an area could get resized/partially reused with a different charging context? A clarification comment would be really handy. -- Michal Hocko SUSE Labs