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-rw-r--r--arch/ia64/include/asm/thread_info.h6
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--include/linux/sched.h3
-rw-r--r--include/linux/sched/task_stack.h2
-rw-r--r--kernel/Kconfig.preempt12
-rw-r--r--kernel/entry/common.c14
-rw-r--r--kernel/exit.c1
-rw-r--r--kernel/fork.c263
-rw-r--r--kernel/signal.c40
9 files changed, 241 insertions, 101 deletions
diff --git a/arch/ia64/include/asm/thread_info.h b/arch/ia64/include/asm/thread_info.h
index 51d20cb37706..1684716f0820 100644
--- a/arch/ia64/include/asm/thread_info.h
+++ b/arch/ia64/include/asm/thread_info.h
@@ -55,15 +55,15 @@ struct thread_info {
#ifndef ASM_OFFSETS_C
/* how to get the thread information struct from C */
#define current_thread_info() ((struct thread_info *) ((char *) current + IA64_TASK_SIZE))
-#define alloc_thread_stack_node(tsk, node) \
+#define arch_alloc_thread_stack_node(tsk, node) \
((unsigned long *) ((char *) (tsk) + IA64_TASK_SIZE))
#define task_thread_info(tsk) ((struct thread_info *) ((char *) (tsk) + IA64_TASK_SIZE))
#else
#define current_thread_info() ((struct thread_info *) 0)
-#define alloc_thread_stack_node(tsk, node) ((unsigned long *) 0)
+#define arch_alloc_thread_stack_node(tsk, node) ((unsigned long *) 0)
#define task_thread_info(tsk) ((struct thread_info *) 0)
#endif
-#define free_thread_stack(tsk) /* nothing */
+#define arch_free_thread_stack(tsk) /* nothing */
#define task_stack_page(tsk) ((void *)(tsk))
#define __HAVE_THREAD_FUNCTIONS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 391c4cac8958..a4f6672d0cb5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -120,6 +120,7 @@ config X86
select ARCH_WANTS_NO_INSTR
select ARCH_WANT_HUGE_PMD_SHARE
select ARCH_WANT_LD_ORPHAN_WARN
+ select ARCH_WANTS_RT_DELAYED_SIGNALS
select ARCH_WANTS_THP_SWAP if X86_64
select ARCH_HAS_PARANOID_L1D_FLUSH
select BUILDTIME_TABLE_SORT
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4e5de3aed410..aab75966396f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1090,6 +1090,9 @@ struct task_struct {
/* Restored if set_restore_sigmask() was used: */
sigset_t saved_sigmask;
struct sigpending pending;
+#ifdef CONFIG_RT_DELAYED_SIGNALS
+ struct kernel_siginfo forced_info;
+#endif
unsigned long sas_ss_sp;
size_t sas_ss_size;
unsigned int sas_ss_flags;
diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index d10150587d81..892562ebbd3a 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -79,6 +79,8 @@ static inline void *try_get_task_stack(struct task_struct *tsk)
static inline void put_task_stack(struct task_struct *tsk) {}
#endif
+void exit_task_stack_account(struct task_struct *tsk);
+
#define task_stack_end_corrupted(task) \
(*(end_of_stack(task)) != STACK_END_MAGIC)
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index ce77f0265660..5644abd5f8a8 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -132,4 +132,14 @@ config SCHED_CORE
which is the likely usage by Linux distributions, there should
be no measurable impact on performance.
-
+config ARCH_WANTS_RT_DELAYED_SIGNALS
+ bool
+ help
+ This option is selected by architectures where raising signals
+ can happen in atomic contexts on PREEMPT_RT enabled kernels. This
+ option delays raising the signal until the return to user space
+ loop where it is also delivered. X86 requires this to deliver
+ signals from trap handlers which run on IST stacks.
+
+config RT_DELAYED_SIGNALS
+ def_bool PREEMPT_RT && ARCH_WANTS_RT_DELAYED_SIGNALS
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index bad713684c2e..0543a2c92f20 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -148,6 +148,18 @@ static void handle_signal_work(struct pt_regs *regs, unsigned long ti_work)
arch_do_signal_or_restart(regs, ti_work & _TIF_SIGPENDING);
}
+#ifdef CONFIG_RT_DELAYED_SIGNALS
+static inline void raise_delayed_signal(void)
+{
+ if (unlikely(current->forced_info.si_signo)) {
+ force_sig_info(&current->forced_info);
+ current->forced_info.si_signo = 0;
+ }
+}
+#else
+static inline void raise_delayed_signal(void) { }
+#endif
+
static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
unsigned long ti_work)
{
@@ -162,6 +174,8 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
if (ti_work & _TIF_NEED_RESCHED)
schedule();
+ raise_delayed_signal();
+
if (ti_work & _TIF_UPROBE)
uprobe_notify_resume(regs);
diff --git a/kernel/exit.c b/kernel/exit.c
index b00a25bb4ab9..c303cffe7fdb 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -845,6 +845,7 @@ void __noreturn do_exit(long code)
put_page(tsk->task_frag.page);
validate_creds_for_do_exit(tsk);
+ exit_task_stack_account(tsk);
check_stack_usage();
preempt_disable();
diff --git a/kernel/fork.c b/kernel/fork.c
index b441a81f5fa9..d74c30b6733b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -186,7 +186,7 @@ static inline void free_task_struct(struct task_struct *tsk)
*/
# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
-#ifdef CONFIG_VMAP_STACK
+# ifdef CONFIG_VMAP_STACK
/*
* vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
* flush. Try to minimize the number of calls by caching stacks.
@@ -194,6 +194,41 @@ static inline void free_task_struct(struct task_struct *tsk)
#define NR_CACHED_STACKS 2
static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
+struct vm_stack {
+ struct rcu_head rcu;
+ struct vm_struct *stack_vm_area;
+};
+
+static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
+{
+ unsigned int i;
+
+ for (i = 0; i < NR_CACHED_STACKS; i++) {
+ if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
+ continue;
+ return true;
+ }
+ return false;
+}
+
+static void thread_stack_free_rcu(struct rcu_head *rh)
+{
+ struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
+
+ if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
+ return;
+
+ vfree(vm_stack);
+}
+
+static void thread_stack_delayed_free(struct task_struct *tsk)
+{
+ struct vm_stack *vm_stack = tsk->stack;
+
+ vm_stack->stack_vm_area = tsk->stack_vm_area;
+ call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
+}
+
static int free_vm_stack_cache(unsigned int cpu)
{
struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
@@ -211,11 +246,35 @@ static int free_vm_stack_cache(unsigned int cpu)
return 0;
}
-#endif
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
+static int memcg_charge_kernel_stack(struct vm_struct *vm)
{
-#ifdef CONFIG_VMAP_STACK
+ int i;
+ int ret;
+
+ 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;
+ }
+ 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++)
+ memcg_kmem_uncharge_page(vm->pages[i], 0);
+ return ret;
+}
+
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
+ struct vm_struct *vm;
void *stack;
int i;
@@ -233,9 +292,14 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
/* Clear stale pointers from reused stack. */
memset(s->addr, 0, THREAD_SIZE);
+ if (memcg_charge_kernel_stack(s)) {
+ vfree(s->addr);
+ return -ENOMEM;
+ }
+
tsk->stack_vm_area = s;
tsk->stack = s->addr;
- return s->addr;
+ return 0;
}
/*
@@ -248,71 +312,95 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
THREADINFO_GFP & ~__GFP_ACCOUNT,
PAGE_KERNEL,
0, node, __builtin_return_address(0));
+ if (!stack)
+ return -ENOMEM;
+ vm = find_vm_area(stack);
+ if (memcg_charge_kernel_stack(vm)) {
+ vfree(stack);
+ return -ENOMEM;
+ }
/*
* We can't call find_vm_area() in interrupt context, and
* free_thread_stack() can be called in interrupt context,
* so cache the vm_struct.
*/
- if (stack) {
- tsk->stack_vm_area = find_vm_area(stack);
- tsk->stack = stack;
- }
- return stack;
-#else
+ tsk->stack_vm_area = vm;
+ tsk->stack = stack;
+ return 0;
+}
+
+static void free_thread_stack(struct task_struct *tsk)
+{
+ if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
+ thread_stack_delayed_free(tsk);
+
+ tsk->stack = NULL;
+ tsk->stack_vm_area = NULL;
+}
+
+# else /* !CONFIG_VMAP_STACK */
+
+static void thread_stack_free_rcu(struct rcu_head *rh)
+{
+ __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
+}
+
+static void thread_stack_delayed_free(struct task_struct *tsk)
+{
+ struct rcu_head *rh = tsk->stack;
+
+ call_rcu(rh, thread_stack_free_rcu);
+}
+
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
struct page *page = alloc_pages_node(node, THREADINFO_GFP,
THREAD_SIZE_ORDER);
if (likely(page)) {
tsk->stack = kasan_reset_tag(page_address(page));
- return tsk->stack;
+ return 0;
}
- return NULL;
-#endif
+ return -ENOMEM;
}
-static inline void free_thread_stack(struct task_struct *tsk)
+static void free_thread_stack(struct task_struct *tsk)
{
-#ifdef CONFIG_VMAP_STACK
- struct vm_struct *vm = task_stack_vm_area(tsk);
-
- if (vm) {
- int i;
+ thread_stack_delayed_free(tsk);
+ tsk->stack = NULL;
+}
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
- memcg_kmem_uncharge_page(vm->pages[i], 0);
+# endif /* CONFIG_VMAP_STACK */
+# else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
- for (i = 0; i < NR_CACHED_STACKS; i++) {
- if (this_cpu_cmpxchg(cached_stacks[i],
- NULL, tsk->stack_vm_area) != NULL)
- continue;
+static struct kmem_cache *thread_stack_cache;
- return;
- }
+static void thread_stack_free_rcu(struct rcu_head *rh)
+{
+ kmem_cache_free(thread_stack_cache, rh);
+}
- vfree_atomic(tsk->stack);
- return;
- }
-#endif
+static void thread_stack_delayed_free(struct task_struct *tsk)
+{
+ struct rcu_head *rh = tsk->stack;
- __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
+ call_rcu(rh, thread_stack_free_rcu);
}
-# else
-static struct kmem_cache *thread_stack_cache;
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
- int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
unsigned long *stack;
stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
stack = kasan_reset_tag(stack);
tsk->stack = stack;
- return stack;
+ return stack ? 0 : -ENOMEM;
}
static void free_thread_stack(struct task_struct *tsk)
{
- kmem_cache_free(thread_stack_cache, tsk->stack);
+ thread_stack_delayed_free(tsk);
+ tsk->stack = NULL;
}
void thread_stack_cache_init(void)
@@ -322,8 +410,26 @@ void thread_stack_cache_init(void)
THREAD_SIZE, NULL);
BUG_ON(thread_stack_cache == NULL);
}
-# endif
-#endif
+
+# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
+#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
+
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
+ unsigned long *stack;
+
+ stack = arch_alloc_thread_stack_node(tsk, node);
+ tsk->stack = stack;
+ return stack ? 0 : -ENOMEM;
+}
+
+static void free_thread_stack(struct task_struct *tsk)
+{
+ arch_free_thread_stack(tsk);
+ tsk->stack = NULL;
+}
+
+#endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
/* SLAB cache for signal_struct structures (tsk->signal) */
static struct kmem_cache *signal_cachep;
@@ -380,50 +486,34 @@ void vm_area_free(struct vm_area_struct *vma)
static void account_kernel_stack(struct task_struct *tsk, int account)
{
- void *stack = task_stack_page(tsk);
- struct vm_struct *vm = task_stack_vm_area(tsk);
-
- if (vm) {
+ if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+ struct vm_struct *vm = 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,
account * (PAGE_SIZE / 1024));
} else {
+ void *stack = task_stack_page(tsk);
+
/* All stack pages are in the same node. */
mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
account * (THREAD_SIZE / 1024));
}
}
-static int memcg_charge_kernel_stack(struct task_struct *tsk)
+void exit_task_stack_account(struct task_struct *tsk)
{
-#ifdef CONFIG_VMAP_STACK
- struct vm_struct *vm = task_stack_vm_area(tsk);
- int ret;
-
- BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
+ account_kernel_stack(tsk, -1);
- if (vm) {
+ if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+ struct vm_struct *vm;
int i;
- BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
-
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
- /*
- * 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.
- */
- ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
- 0);
- if (ret)
- return ret;
- }
+ vm = task_stack_vm_area(tsk);
+ for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+ memcg_kmem_uncharge_page(vm->pages[i], 0);
}
-#endif
- return 0;
}
static void release_task_stack(struct task_struct *tsk)
@@ -431,12 +521,7 @@ static void release_task_stack(struct task_struct *tsk)
if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
return; /* Better to leak the stack than to free prematurely */
- account_kernel_stack(tsk, -1);
free_thread_stack(tsk);
- tsk->stack = NULL;
-#ifdef CONFIG_VMAP_STACK
- tsk->stack_vm_area = NULL;
-#endif
}
#ifdef CONFIG_THREAD_INFO_IN_TASK
@@ -875,8 +960,6 @@ void set_task_stack_end_magic(struct task_struct *tsk)
static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
{
struct task_struct *tsk;
- unsigned long *stack;
- struct vm_struct *stack_vm_area __maybe_unused;
int err;
if (node == NUMA_NO_NODE)
@@ -885,32 +968,18 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
if (!tsk)
return NULL;
- stack = alloc_thread_stack_node(tsk, node);
- if (!stack)
+ err = arch_dup_task_struct(tsk, orig);
+ if (err)
goto free_tsk;
- if (memcg_charge_kernel_stack(tsk))
- goto free_stack;
-
- stack_vm_area = task_stack_vm_area(tsk);
-
- err = arch_dup_task_struct(tsk, orig);
+ err = alloc_thread_stack_node(tsk, node);
+ if (err)
+ goto free_tsk;
- /*
- * arch_dup_task_struct() clobbers the stack-related fields. Make
- * sure they're properly initialized before using any stack-related
- * functions again.
- */
- tsk->stack = stack;
-#ifdef CONFIG_VMAP_STACK
- tsk->stack_vm_area = stack_vm_area;
-#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
refcount_set(&tsk->stack_refcount, 1);
#endif
-
- if (err)
- goto free_stack;
+ account_kernel_stack(tsk, 1);
err = scs_prepare(tsk, node);
if (err)
@@ -954,8 +1023,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
tsk->wake_q.next = NULL;
tsk->worker_private = NULL;
- account_kernel_stack(tsk, 1);
-
kcov_task_init(tsk);
kmap_local_fork(tsk);
@@ -978,6 +1045,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
return tsk;
free_stack:
+ exit_task_stack_account(tsk);
free_thread_stack(tsk);
free_tsk:
free_task_struct(tsk);
@@ -2450,6 +2518,7 @@ bad_fork_cleanup_count:
exit_creds(p);
bad_fork_free:
WRITE_ONCE(p->__state, TASK_DEAD);
+ exit_task_stack_account(p);
put_task_stack(p);
delayed_free_task(p);
fork_out:
diff --git a/kernel/signal.c b/kernel/signal.c
index 9b04631acde8..e93de6daa188 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1308,6 +1308,43 @@ enum sig_handler {
};
/*
+ * On some archictectures, PREEMPT_RT has to delay sending a signal from a
+ * trap since it cannot enable preemption, and the signal code's
+ * spin_locks turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME
+ * which will send the signal on exit of the trap.
+ */
+#ifdef CONFIG_RT_DELAYED_SIGNALS
+static inline bool force_sig_delayed(struct kernel_siginfo *info,
+ struct task_struct *t)
+{
+ if (!in_atomic())
+ return false;
+
+ if (WARN_ON_ONCE(t->forced_info.si_signo))
+ return true;
+
+ if (is_si_special(info)) {
+ WARN_ON_ONCE(info != SEND_SIG_PRIV);
+ t->forced_info.si_signo = info->si_signo;
+ t->forced_info.si_errno = 0;
+ t->forced_info.si_code = SI_KERNEL;
+ t->forced_info.si_pid = 0;
+ t->forced_info.si_uid = 0;
+ } else {
+ t->forced_info = *info;
+ }
+ set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+ return true;
+}
+#else
+static inline bool force_sig_delayed(struct kernel_siginfo *info,
+ struct task_struct *t)
+{
+ return false;
+}
+#endif
+
+/*
* Force a signal that the process can't ignore: if necessary
* we unblock the signal and change any SIG_IGN to SIG_DFL.
*
@@ -1327,6 +1364,9 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
struct k_sigaction *action;
int sig = info->si_signo;
+ if (force_sig_delayed(info, t))
+ return 0;
+
spin_lock_irqsave(&t->sighand->siglock, flags);
action = &t->sighand->action[sig-1];
ignored = action->sa.sa_handler == SIG_IGN;
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-27 14:20:23 +0000