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Peter Anvin" , Andy Lutomirski , Xin Li , Peter Zijlstra , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Uladzislau Rezki , Kees Cook Cc: David Stevens , linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" From: Pasha Tatashin In many places number of pages in the stack is detremined 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. However, with dynamic stacks, the number of pages in vm_area will grow with stack, therefore, use vm_area->nr_pages to determine the actual number of pages allocated in stack. Signed-off-by: Pasha Tatashin [Rebased, also skipped intermediary helper variable nr_pages] Signed-off-by: Linus Walleij Signed-off-by: David Stevens --- kernel/fork.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index bc2bf58b93b6..8961b895bf05 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -312,9 +312,7 @@ 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; @@ -484,7 +482,7 @@ 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 { @@ -505,7 +503,7 @@ 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); } } -- 2.54.0.rc2.544.gc7ae2d5bb8-goog