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fork: clean-up naming of vm_stack/vm_struct variables in vmap stacks code

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There are two data types: "struct vm_struct" and "struct vm_stack" that
have the same local variable names: vm_stack, or vm, or s, which makes the
code confusing to read.

Change the code so the naming is consistent:

struct vm_struct is always called vm_area
struct vm_stack is always called vm_stack

One change altering vfree(vm_stack) to vfree(vm_area->addr) may look like
a semantic change but it is not: vm_area->addr points to the vm_stack. 
This was done to improve readability.

[linus.walleij@linaro.org: rebased and added new users of the variable names, address review comments]
Link: https://lore.kernel.org/20240311164638.2015063-4-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20250509-fork-fixes-v3-2-e6c69dd356f2@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Pasha Tatashin
2025-05-09 08:29:27 +02:00
committed by Andrew Morton
parent 85e1f758b6
commit 90eb270d8e
1 changed files with 29 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/fork.c
+29 -31
View File
@@ -198,14 +198,14 @@ struct vm_stack {
struct vm_struct *stack_vm_area;
};
static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
static bool try_release_thread_stack_to_cache(struct vm_struct *vm_area)
{
unsigned int i;
for (i = 0; i < NR_CACHED_STACKS; i++) {
struct vm_struct *tmp = NULL;
if (this_cpu_try_cmpxchg(cached_stacks[i], &tmp, vm))
if (this_cpu_try_cmpxchg(cached_stacks[i], &tmp, vm_area))
return true;
}
return false;
@@ -214,11 +214,12 @@ static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
static void thread_stack_free_rcu(struct rcu_head *rh)
{
struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
struct vm_struct *vm_area = vm_stack->stack_vm_area;
if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
return;
vfree(vm_stack);
vfree(vm_area->addr);
}
static void thread_stack_delayed_free(struct task_struct *tsk)
@@ -231,32 +232,32 @@ static void thread_stack_delayed_free(struct task_struct *tsk)
static int free_vm_stack_cache(unsigned int cpu)
{
struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
struct vm_struct **cached_vm_stack_areas = per_cpu_ptr(cached_stacks, cpu);
int i;
for (i = 0; i < NR_CACHED_STACKS; i++) {
struct vm_struct *vm_stack = cached_vm_stacks[i];
struct vm_struct *vm_area = cached_vm_stack_areas[i];
if (!vm_stack)
if (!vm_area)
continue;
vfree(vm_stack->addr);
cached_vm_stacks[i] = NULL;
vfree(vm_area->addr);
cached_vm_stack_areas[i] = NULL;
}
return 0;
}
static int memcg_charge_kernel_stack(struct vm_struct *vm)
static int memcg_charge_kernel_stack(struct vm_struct *vm_area)
{
int i;
int ret;
int nr_charged = 0;
BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
BUG_ON(vm_area->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);
ret = memcg_kmem_charge_page(vm_area->pages[i], GFP_KERNEL, 0);
if (ret)
goto err;
nr_charged++;
@@ -264,38 +265,35 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
return 0;
err:
for (i = 0; i < nr_charged; i++)
memcg_kmem_uncharge_page(vm->pages[i], 0);
memcg_kmem_uncharge_page(vm_area->pages[i], 0);
return ret;
}
static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
struct vm_struct *vm;
struct vm_struct *vm_area;
void *stack;
int i;
for (i = 0; i < NR_CACHED_STACKS; i++) {
struct vm_struct *s;
s = this_cpu_xchg(cached_stacks[i], NULL);
if (!s)
vm_area = this_cpu_xchg(cached_stacks[i], NULL);
if (!vm_area)
continue;
/* Reset stack metadata. */
kasan_unpoison_range(s->addr, THREAD_SIZE);
kasan_unpoison_range(vm_area->addr, THREAD_SIZE);
stack = kasan_reset_tag(s->addr);
stack = kasan_reset_tag(vm_area->addr);
/* Clear stale pointers from reused stack. */
memset(stack, 0, THREAD_SIZE);
if (memcg_charge_kernel_stack(s)) {
vfree(s->addr);
if (memcg_charge_kernel_stack(vm_area)) {
vfree(vm_area->addr);
return -ENOMEM;
}
tsk->stack_vm_area = s;
tsk->stack_vm_area = vm_area;
tsk->stack = stack;
return 0;
}
@@ -311,8 +309,8 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
if (!stack)
return -ENOMEM;
vm = find_vm_area(stack);
if (memcg_charge_kernel_stack(vm)) {
vm_area = find_vm_area(stack);
if (memcg_charge_kernel_stack(vm_area)) {
vfree(stack);
return -ENOMEM;
}
@@ -321,7 +319,7 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
* free_thread_stack() can be called in interrupt context,
* so cache the vm_struct.
*/
tsk->stack_vm_area = vm;
tsk->stack_vm_area = vm_area;
stack = kasan_reset_tag(stack);
tsk->stack = stack;
return 0;
@@ -517,11 +515,11 @@ void vm_area_free(struct vm_area_struct *vma)
static void account_kernel_stack(struct task_struct *tsk, int account)
{
if (IS_ENABLED(CONFIG_VMAP_STACK)) {
struct vm_struct *vm = task_stack_vm_area(tsk);
struct vm_struct *vm_area = task_stack_vm_area(tsk);
int i;
for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
mod_lruvec_page_state(vm_area->pages[i], NR_KERNEL_STACK_KB,
account * (PAGE_SIZE / 1024));
} else {
void *stack = task_stack_page(tsk);
@@ -537,12 +535,12 @@ void exit_task_stack_account(struct task_struct *tsk)
account_kernel_stack(tsk, -1);
if (IS_ENABLED(CONFIG_VMAP_STACK)) {
struct vm_struct *vm;
struct vm_struct *vm_area;
int i;
vm = task_stack_vm_area(tsk);
vm_area = task_stack_vm_area(tsk);
for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
memcg_kmem_uncharge_page(vm->pages[i], 0);
memcg_kmem_uncharge_page(vm_area->pages[i], 0);
}
}