[PATCH 2/4] ring-buffer: Use kvzalloc_objs for remote buffer subbuf_ids

[Vincent Donnefort <vdonnefort@google.com>]

Creating a remote ring buffer requires allocating an array of bpage. For
large ring buffers, this contiguous allocation is likely to fail with
memory fragmentation.

Switch it to kvzalloc_objs() to use the vmalloc fallback under memory
pressure.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
---
 kernel/trace/ring_buffer.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f9be87c2cc3d..1a158a24b3c8 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2620,8 +2620,8 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, unsigned long nr_pages, int
 		cpu_buffer->remote = buffer->remote;
 		cpu_buffer->meta_page = (struct trace_buffer_meta *)(void *)desc->meta_va;
 		cpu_buffer->nr_pages = nr_pages;
-		cpu_buffer->subbuf_ids = kzalloc_objs(*cpu_buffer->subbuf_ids,
-						      cpu_buffer->nr_pages + 1);
+		cpu_buffer->subbuf_ids = kvzalloc_objs(*cpu_buffer->subbuf_ids,
+						       cpu_buffer->nr_pages + 1);
 		if (!cpu_buffer->subbuf_ids)
 			goto fail_free_reader;
 
@@ -2681,7 +2681,7 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, unsigned long nr_pages, int
 	return_ptr(cpu_buffer);
 
  fail_free_reader:
-	kfree(cpu_buffer->subbuf_ids);
+	kvfree(cpu_buffer->subbuf_ids);
 	free_buffer_page(cpu_buffer->reader_page);
 
 	return NULL;
@@ -2694,8 +2694,8 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
 
 	irq_work_sync(&cpu_buffer->irq_work.work);
 
-	if (cpu_buffer->remote)
-		kfree(cpu_buffer->subbuf_ids);
+	kvfree(cpu_buffer->subbuf_ids);
+	cpu_buffer->subbuf_ids = NULL;
 
 	free_buffer_page(cpu_buffer->reader_page);
 
-- 
2.55.0.1082.g2b9226bbc0-goog