linux-kernel - Re: [PATCH v1] kernel/trace:check the val against the available mem

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Date:   Fri, 30 Mar 2018 17:42:09 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Zhaoyang Huang <huangzhaoyang@...il.com>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        kernel-patch-test@...ts.linaro.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joel Fernandes <joelaf@...gle.com>,
        Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>
Subject: Re: [PATCH v1] kernel/trace:check the val against the available mem

On Fri, 30 Mar 2018 17:30:31 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> I'll take a look at si_mem_available() that Joel suggested and see if
> we can make that work.

Wow, this appears to work great! Joel and Zhaoyang, can you test this?

-- Steve

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index a2fd3893cc02..32a803626ee2 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1164,6 +1164,11 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
 	struct buffer_page *bpage, *tmp;
 	long i;
 
+	/* Check if the available memory is there first */
+	i = si_mem_available();
+	if (i < nr_pages)
+		return -ENOMEM;
+
 	for (i = 0; i < nr_pages; i++) {
 		struct page *page;
 		/*