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authorHaifeng Xu <haifeng.xu@shopee.com>2023-05-08 06:44:58 +0000
committerAndrew Morton <akpm@linux-foundation.org>2023-06-09 17:44:13 -0700
commit4e2f6342ccaf9d8beb33b398cc2862769c7d2a3b (patch)
tree040886ae0f0b89c4c81c0aed89f69c750bf7d33f /kernel/fork.c
parent3db55767da7427cebc49e22b25b5f50ff455add6 (diff)
fork: optimize memcg_charge_kernel_stack() a bit
Since commit f1c1a9ee00e4 ("fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK"), memcg_charge_kernel_stack() has been moved into CONFIG_VMAP_STACK block, so the CONFIG_VMAP_STACK check can be removed. Furthermore, memcg_charge_kernel_stack() is only invoked by alloc_thread_stack_node() instead of dup_task_struct(). If memcg_kmem_charge_page() fails, the uncharge process is handled in memcg_charge_kernel_stack() itself instead of free_thread_stack(), so remove the incorrect comments. If memcg_charge_kernel_stack() fails to charge pages used by kernel stack, only charged pages need to be uncharged. It's unnecessary to uncharge those pages which memory cgroup pointer is NULL. [akpm@linux-foundation.org: remove assertion that PAGE_SIZE is a multiple of 1k] Link: https://lkml.kernel.org/r/20230508064458.32855-1-haifeng.xu@shopee.com Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Daniel Bristot de Oliveira <bristot@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index ed4e01daccaa..d17995934eb4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -252,23 +252,19 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
{
int i;
int ret;
+ int nr_charged = 0;
- BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
if (ret)
goto err;
+ nr_charged++;
}
return 0;
err:
- /*
- * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
- * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
- * ignore this page.
- */
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+ for (i = 0; i < nr_charged; i++)
memcg_kmem_uncharge_page(vm->pages[i], 0);
return ret;
}