From: Pasha Tatashin <[email protected]> In many places number of pages in the stack is determined via (THREAD_SIZE / PAGE_SIZE). There is also a BUG_ON() that ensures that (THREAD_SIZE / PAGE_SIZE) is indeed equals to vm_area->nr_pages.
In the next patches the kernel stack size will not be a compile time constant and would be less than or equal THREAD_SIZE based on a command line arg. Therefore, use vm_area->nr_pages to determine the actual number of pages allocated in stack. Signed-off-by: Pasha Tatashin <[email protected]> [Rebased, also skipped intermediary helper variable nr_pages] Signed-off-by: Linus Walleij <[email protected]> Signed-off-by: David Stevens <[email protected]> [Update commit message] Signed-off-by: Mostafa Saleh <[email protected]> --- kernel/fork.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 5ef413368912..2065693e762c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -315,9 +315,7 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm_area) int ret; int nr_charged = 0; - BUG_ON(vm_area->nr_pages != THREAD_SIZE / PAGE_SIZE); - - for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) { + for (i = 0; i < vm_area->nr_pages; i++) { ret = memcg_kmem_charge_page(vm_area->pages[i], GFP_KERNEL, 0); if (ret) goto err; @@ -488,7 +486,7 @@ static void account_kernel_stack(struct task_struct *tsk, int account) struct vm_struct *vm_area = task_stack_vm_area(tsk); int i; - for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) + for (i = 0; i < vm_area->nr_pages; i++) mod_lruvec_page_state(vm_area->pages[i], NR_KERNEL_STACK_KB, account * (PAGE_SIZE / 1024)); } else { @@ -509,7 +507,7 @@ void exit_task_stack_account(struct task_struct *tsk) int i; vm_area = task_stack_vm_area(tsk); - for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) + for (i = 0; i < vm_area->nr_pages; i++) memcg_kmem_uncharge_page(vm_area->pages[i], 0); } } -- 2.56.0.rc1.315.gc6ed9934b7-goog
