4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ingo Molnar <[email protected]> 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" <[email protected]> Bisected-by: Borislav Petkov <[email protected]> Analyzed-by: Peter Zijlstra <[email protected]> Cc: Julien Thierry <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: <[email protected]> Fixes: 9dff0aa95a32 ("perf/core: Don't WARN() for impossible ring-buffer sizes") Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 @@ -637,7 +637,7 @@ 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);
