4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ingo Molnar <mi...@kernel.org>
commit 528871b456026e6127d95b1b2bd8e3a003dc1614 upstream.
The following commit:
9dff0aa95a32 ("perf/core: Don't WARN() for impossible ring-buffer sizes")
results in perf recording failures with larger mmap areas:
root@skl:/tmp# perf record -g -a
failed to mmap with 12 (Cannot allocate memory)
The root cause is that the following condition is buggy:
if (order_base_2(size) >= MAX_ORDER)
goto fail;
The problem is that @size is in bytes and MAX_ORDER is in pages,
so the right test is:
if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER)
goto fail;
Fix it.
Reported-by: "Jin, Yao" <yao....@linux.intel.com>
Bisected-by: Borislav Petkov <b...@alien8.de>
Analyzed-by: Peter Zijlstra <pet...@infradead.org>
Cc: Julien Thierry <julien.thie...@arm.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: <sta...@vger.kernel.org>
Fixes: 9dff0aa95a32 ("perf/core: Don't WARN() for impossible ring-buffer sizes")
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
kernel/events/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -724,7 +724,7 @@ struct ring_buffer *rb_alloc(int nr_page
size = sizeof(struct ring_buffer);
size += nr_pages * sizeof(void *);
- if (order_base_2(size) >= MAX_ORDER)
+ if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER)
goto fail;
rb = kzalloc(size, GFP_KERNEL);
