Today we account each page individually to the memcg, which works well
enough, if a little inefficiently (N atomic operations per page instead
of N per allocation). Unfortunately, the stats can get out of sync when
i915 calls vmap() with VM_MAP_PUT_PAGES. The pages being passed were not
allocated by vmalloc, so the MEMCG_VMALLOC counter was never incremented.
But it is decremented when the pages are freed with vfree().
Solve all of this by tracking the memcg at the vm_struct level.
This logic has to live in the memcontrol file as it calls several
functions which are currently static.
Fixes: b944afc9d64d (mm: add a VM_MAP_PUT_PAGES flag for vmap)
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 7 ++++++
include/linux/vmalloc.h | 3 +++
mm/memcontrol.c | 46 ++++++++++++++++++++++++++++++++++++++
mm/vmalloc.c | 14 ++++++------
4 files changed, 63 insertions(+), 7 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5502aa8e138e..83ebcadebba6 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1676,6 +1676,10 @@ static inline struct obj_cgroup *get_obj_cgroup_from_current(void)
int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);
+int obj_cgroup_charge_vmalloc(struct obj_cgroup **objcgp,
+ unsigned int nr_pages, gfp_t gfp);
+void obj_cgroup_uncharge_vmalloc(struct obj_cgroup *objcgp,
+ unsigned int nr_pages);
extern struct static_key_false memcg_bpf_enabled_key;
static inline bool memcg_bpf_enabled(void)
@@ -1756,6 +1760,9 @@ static inline void __memcg_kmem_uncharge_page(struct page *page, int order)
{
}
+/* Must be macros to avoid dereferencing objcg in vm_struct */
+#define obj_cgroup_charge_vmalloc(objcgp, nr_pages, gfp) 0
+#define obj_cgroup_uncharge_vmalloc(objcg, nr_pages) do { } while (0)
static inline struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio)
{
return NULL;
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 31e9ffd936e3..ec7c2d607382 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -60,6 +60,9 @@ struct vm_struct {
#endif
unsigned int nr_pages;
phys_addr_t phys_addr;
+#ifdef CONFIG_MEMCG
+ struct obj_cgroup *objcg;
+#endif
const void *caller;
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7b3503d12aaf..629bffc3e26d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5472,4 +5472,50 @@ static int __init mem_cgroup_swap_init(void)
}
subsys_initcall(mem_cgroup_swap_init);
+/**
+ * obj_cgroup_charge_vmalloc - Charge vmalloc memory
+ * @objcgp: Pointer to an object cgroup
+ * @nr_pages: Number of pages
+ * @gfp: Memory allocation flags
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int obj_cgroup_charge_vmalloc(struct obj_cgroup **objcgp,
+ unsigned int nr_pages, gfp_t gfp)
+{
+ struct obj_cgroup *objcg;
+ int err;
+
+ if (mem_cgroup_disabled() || !(gfp & __GFP_ACCOUNT))
+ return 0;
+
+ objcg = current_obj_cgroup();
+ if (!objcg)
+ return 0;
+
+ err = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
+ if (err)
+ return err;
+ obj_cgroup_get(objcg);
+ mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_VMALLOC, nr_pages);
+ *objcgp = objcg;
+
+ return 0;
+}
+
+/**
+ * obj_cgroup_uncharge_vmalloc - Uncharge vmalloc memory
+ * @objcg: The object cgroup
+ * @nr_pages: Number of pages
+ */
+void obj_cgroup_uncharge_vmalloc(struct obj_cgroup *objcg,
+ unsigned int nr_pages)
+{
+ if (!objcg)
+ return;
+ mod_memcg_state(objcg->memcg, MEMCG_VMALLOC, 0L - nr_pages);
+ obj_cgroup_uncharge_pages(objcg, nr_pages);
+ obj_cgroup_put(objcg);
+}
+
#endif /* CONFIG_SWAP */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f009b21705c1..438995d2f9f8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3374,7 +3374,6 @@ void vfree(const void *addr)
struct page *page = vm->pages[i];
BUG_ON(!page);
- 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
@@ -3383,6 +3382,7 @@ void vfree(const void *addr)
cond_resched();
}
atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages);
+ obj_cgroup_uncharge_vmalloc(vm->objcg, vm->nr_pages);
kvfree(vm->pages);
kfree(vm);
}
@@ -3536,6 +3536,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
struct page *page;
int i;
+ /* Accounting handled in caller */
+ gfp &= ~__GFP_ACCOUNT;
+
/*
* For order-0 pages we make use of bulk allocator, if
* the page array is partly or not at all populated due
@@ -3669,12 +3672,9 @@ 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);
- }
+ ret = obj_cgroup_charge_vmalloc(&area->objcg, gfp_mask, area->nr_pages);
+ if (ret)
+ goto fail;
/*
* If not enough pages were obtained to accomplish an
--
2.45.2
