ring-buffer: Add rb_check_bpage in __rb_allocate_pages

It may be better to check each page is aligned by 4 bytes. The 2
least significant bits of the address will be used as flags.

Link: https://lkml.kernel.org/r/20201015113842.2921-1-hqjagain@gmail.com
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index e97ecf7..e03bc4e 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1423,7 +1423,8 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
        return 0;
 }
 
-static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
+static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
+               long nr_pages, struct list_head *pages)
 {
        struct buffer_page *bpage, *tmp;
        bool user_thread = current->mm != NULL;
@@ -1463,13 +1464,15 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
                struct page *page;
 
                bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
-                                   mflags, cpu_to_node(cpu));
+                                   mflags, cpu_to_node(cpu_buffer->cpu));
                if (!bpage)
                        goto free_pages;
 
+               rb_check_bpage(cpu_buffer, bpage);
+
                list_add(&bpage->list, pages);
 
-               page = alloc_pages_node(cpu_to_node(cpu), mflags, 0);
+               page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), mflags, 0);
                if (!page)
                        goto free_pages;
                bpage->page = page_address(page);
@@ -1501,7 +1504,7 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 
        WARN_ON(!nr_pages);
 
-       if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu))
+       if (__rb_allocate_pages(cpu_buffer, nr_pages, &pages))
                return -ENOMEM;
 
        /*
@@ -2008,8 +2011,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
                         * allocated without receiving ENOMEM
                         */
                        INIT_LIST_HEAD(&cpu_buffer->new_pages);
-                       if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update,
-                                               &cpu_buffer->new_pages, cpu)) {
+                       if (__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,
+                                               &cpu_buffer->new_pages)) {
                                /* not enough memory for new pages */
                                err = -ENOMEM;
                                goto out_err;
@@ -2074,8 +2077,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
 
                INIT_LIST_HEAD(&cpu_buffer->new_pages);
                if (cpu_buffer->nr_pages_to_update > 0 &&
-                       __rb_allocate_pages(cpu_buffer->nr_pages_to_update,
-                                           &cpu_buffer->new_pages, cpu_id)) {
+                       __rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,
+                                           &cpu_buffer->new_pages)) {
                        err = -ENOMEM;
                        goto out_err;
                }