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Message-ID: <20250403053326.26860-1-shakeel.butt@linux.dev>
Date: Wed, 2 Apr 2025 22:33:26 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Uladzislau Rezki <urezki@...il.com>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Muchun Song <muchun.song@...ux.dev>,
linux-mm@...ck.org,
cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org,
Meta kernel team <kernel-team@...a.com>
Subject: [PATCH] memcg: vmalloc: simplify MEMCG_VMALLOC updates
The vmalloc region can either be charged to a single memcg or none. At
the moment kernel traverses all the pages backing the vmalloc region to
update the MEMCG_VMALLOC stat. However there is no need to look at all
the pages as all those pages will be charged to a single memcg or none.
Simplify the MEMCG_VMALLOC update by just looking at the first page of
the vmalloc region.
Signed-off-by: Shakeel Butt <shakeel.butt@...ux.dev>
---
mm/vmalloc.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 3ed720a787ec..cdae76994488 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3370,12 +3370,12 @@ void vfree(const void *addr)
if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS))
vm_reset_perms(vm);
+ if (vm->nr_pages && !(vm->flags & VM_MAP_PUT_PAGES))
+ mod_memcg_page_state(vm->pages[0], MEMCG_VMALLOC, -vm->nr_pages);
for (i = 0; i < vm->nr_pages; i++) {
struct page *page = vm->pages[i];
BUG_ON(!page);
- if (!(vm->flags & VM_MAP_PUT_PAGES))
- mod_memcg_page_state(page, MEMCG_VMALLOC, -1);
/*
* High-order allocs for huge vmallocs are split, so
* can be freed as an array of order-0 allocations
@@ -3671,12 +3671,9 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
node, page_order, nr_small_pages, area->pages);
atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
- if (gfp_mask & __GFP_ACCOUNT) {
- int i;
-
- for (i = 0; i < area->nr_pages; i++)
- mod_memcg_page_state(area->pages[i], MEMCG_VMALLOC, 1);
- }
+ if (gfp_mask & __GFP_ACCOUNT && area->nr_pages)
+ mod_memcg_page_state(area->pages[0], MEMCG_VMALLOC,
+ area->nr_pages);
/*
* If not enough pages were obtained to accomplish an
--
2.47.1
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