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authorMuchun Song <songmuchun@bytedance.com>2021-04-29 22:56:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 11:20:37 -0700
commit27faca83a7e955e4e0b831d75a8a9a840fe9bae4 (patch)
tree25fb75d43422c6e5520e631696e1c74a1efc3f88 /kernel
parent2840d498e30ce53a3a7cb482a5445efd892c7697 (diff)
downloadlinux-27faca83a7e955e4e0b831d75a8a9a840fe9bae4.tar.bz2
mm: memcontrol: fix kernel stack account
For simplification commit 991e7673859e ("mm: memcontrol: account kernel stack per node") changed the per zone vmalloc backed stack pages accounting to per node. By doing that we have lost a certain precision because those pages might live in different NUMA nodes. In the end NR_KERNEL_STACK_KB exported to the userspace might be over estimated on some nodes while underestimated on others. But this is not a real world problem, just a problem found by reading the code. So there is no actual data to showing how much impact it has on users. This doesn't impose any real problem to correctnes of the kernel behavior as the counter is not used for any internal processing but it can cause some confusion to the userspace. Address the problem by accounting each vmalloc backing page to its own node. Link: https://lkml.kernel.org/r/20210303151843.81156-1-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 0a5d28fe9990..771e0ea90499 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -380,14 +380,17 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
void *stack = task_stack_page(tsk);
struct vm_struct *vm = task_stack_vm_area(tsk);
+ if (vm) {
+ int i;
- /* All stack pages are in the same node. */
- if (vm)
- mod_lruvec_page_state(vm->pages[0], NR_KERNEL_STACK_KB,
- account * (THREAD_SIZE / 1024));
- else
+ for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+ mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
+ account * (PAGE_SIZE / 1024));
+ } else {
+ /* All stack pages are in the same node. */
mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
account * (THREAD_SIZE / 1024));
+ }
}
static int memcg_charge_kernel_stack(struct task_struct *tsk)