On Sat, 26 Oct 2024 06:32:10 -0400 Steven Rostedt <[email protected]> wrote:
> From: Steven Rostedt <[email protected]> > > The ret_stack (shadow stack used by function graph infrastructure) is > created for every task on the system when function graph is enabled. Give > it its own kmem_cache. This will make it easier to see how much memory is > being used specifically for function graph shadow stacks. > > In the future, this size may change and may not be a power of two. Having > its own cache can also keep it from fragmenting memory. > Looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thank youm > Signed-off-by: Steven Rostedt (Google) <[email protected]> > --- > Changes since v1: > https://lore.kernel.org/[email protected] > > - Rebased on top of urgent merged into for-next (uses guard(mutex) now) > > kernel/trace/fgraph.c | 33 ++++++++++++++++++++++++++++----- > 1 file changed, 28 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index 4ce87982966a..001abf376c0c 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -172,6 +172,8 @@ enum { > DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); > int ftrace_graph_active; > > +static struct kmem_cache *fgraph_stack_cachep; > + > static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE]; > static unsigned long fgraph_array_bitmask; > > @@ -1022,8 +1024,11 @@ static int alloc_retstack_tasklist(unsigned long > **ret_stack_list) > int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE; > struct task_struct *g, *t; > > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return -ENOMEM; > + > for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) { > - ret_stack_list[i] = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + ret_stack_list[i] = kmem_cache_alloc(fgraph_stack_cachep, > GFP_KERNEL); > if (!ret_stack_list[i]) { > start = 0; > end = i; > @@ -1054,7 +1059,7 @@ static int alloc_retstack_tasklist(unsigned long > **ret_stack_list) > rcu_read_unlock(); > free: > for (i = start; i < end; i++) > - kfree(ret_stack_list[i]); > + kmem_cache_free(fgraph_stack_cachep, ret_stack_list[i]); > return ret; > } > > @@ -1117,9 +1122,12 @@ void ftrace_graph_init_idle_task(struct task_struct > *t, int cpu) > if (ftrace_graph_active) { > unsigned long *ret_stack; > > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + > ret_stack = per_cpu(idle_ret_stack, cpu); > if (!ret_stack) { > - ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + ret_stack = kmem_cache_alloc(fgraph_stack_cachep, > GFP_KERNEL); > if (!ret_stack) > return; > per_cpu(idle_ret_stack, cpu) = ret_stack; > @@ -1139,7 +1147,10 @@ void ftrace_graph_init_task(struct task_struct *t) > if (ftrace_graph_active) { > unsigned long *ret_stack; > > - ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + > + ret_stack = kmem_cache_alloc(fgraph_stack_cachep, GFP_KERNEL); > if (!ret_stack) > return; > graph_init_task(t, ret_stack); > @@ -1154,7 +1165,11 @@ void ftrace_graph_exit_task(struct task_struct *t) > /* NULL must become visible to IRQs before we free it: */ > barrier(); > > - kfree(ret_stack); > + if (ret_stack) { > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + kmem_cache_free(fgraph_stack_cachep, ret_stack); > + } > } > > #ifdef CONFIG_DYNAMIC_FTRACE > @@ -1294,6 +1309,14 @@ int register_ftrace_graph(struct fgraph_ops *gops) > > guard(mutex)(&ftrace_lock); > > + if (!fgraph_stack_cachep) { > + fgraph_stack_cachep = kmem_cache_create("fgraph_stack", > + SHADOW_STACK_SIZE, > + SHADOW_STACK_SIZE, 0, > NULL); > + if (!fgraph_stack_cachep) > + return -ENOMEM; > + } > + > if (!fgraph_initialized) { > ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph:online", > fgraph_cpu_init, NULL); > -- > 2.45.2 > -- Masami Hiramatsu (Google) <[email protected]>
