UPSTREAM: perf/core: Fix impossible ring-buffer sizes warning

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" <>
Bisected-by: Borislav Petkov <>
Analyzed-by: Peter Zijlstra <>
Cc: Julien Thierry <>
Cc: Mark Rutland <>
Cc: Alexander Shishkin <>
Cc: Arnaldo Carvalho de Melo <>
Cc: Jiri Olsa <>
Cc: Linus Torvalds <>
Cc: Namhyung Kim <>
Cc: Peter Zijlstra <>
Cc: Thomas Gleixner <>
Cc: Greg Kroah-Hartman <>
Cc: <>
Fixes: 9dff0aa95a32 ("perf/core: Don't WARN() for impossible ring-buffer sizes")
Signed-off-by: Ingo Molnar <>
(cherry picked from commit 528871b456026e6127d95b1b2bd8e3a003dc1614)

TEST=perf record -g -a

Change-Id: I418f2b70c3de76d0c59e7f278107eba4b5d80ba2
Signed-off-by: Guenter Roeck <>
Reviewed-by: Sean Paul <>
Reviewed-by: Sonny Rao <>
Reviewed-by: Yu Zhao <>
Reviewed-by: Alexey Alexandrov <>
1 file changed