uprobes: Re-order struct uprobe_task to save some space

On x86_64, with allmodconfig, struct uprobe_task is 72 bytes long, with a
hole and some padding.

	/* size: 72, cachelines: 2, members: 7 */
	/* sum members: 64, holes: 1, sum holes: 4 */
	/* padding: 4 */
	/* forced alignments: 1, forced holes: 1, sum forced holes: 4 */
	/* last cacheline: 8 bytes */

Reorder the structure to fill the hole and avoid the padding.

This way, the whole structure fits in a single cacheline and some memory is
saved when it is allocated.

	/* size: 64, cachelines: 1, members: 7 */
	/* forced alignments: 1 */

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/a9f541d0cedf421f765c77a1fb93d6a979778a88.1730495562.git.christophe.jaillet@wanadoo.fr

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 7a051b5d2edda8654edf8bb5cb2be9832b9d97d3..e0a4c2082245890f9528ee687ad4d883121dbba9 100644 (file)
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -121,6 +121,9 @@ struct hprobe {
 struct uprobe_task {
        enum uprobe_task_state          state;
 
+       unsigned int                    depth;
+       struct return_instance          *return_instances;
+
        union {
                struct {
                        struct arch_uprobe_task autask;
@@ -138,9 +141,6 @@ struct uprobe_task {
        unsigned long                   xol_vaddr;
 
        struct arch_uprobe              *auprobe;
-
-       struct return_instance          *return_instances;
-       unsigned int                    depth;
 };
 
 struct return_consumer {