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| author | Haifeng Xu <haifeng.xu@shopee.com> | 2023-05-08 08:44:58 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-06-10 02:44:13 +0200 |
| commit | 4e2f6342ccaf9d8beb33b398cc2862769c7d2a3b (patch) | |
| tree | 040886ae0f0b89c4c81c0aed89f69c750bf7d33f /kernel/fork.c | |
| parent | add intptr_t (diff) | |
| download | linux-4e2f6342ccaf9d8beb33b398cc2862769c7d2a3b.tar.xz linux-4e2f6342ccaf9d8beb33b398cc2862769c7d2a3b.zip | |
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.c | 10 |
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; } |