| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 54/85] perf/core: Fix impossible ring-buffer sizes warning | Date | Mon, 18 Feb 2019 14:43:20 +0100 |
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4.19-stable review patch. If anyone has any objections, please let me know.
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From: Ingo Molnar <mingo@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.jin@linux.intel.com> Bisected-by: Borislav Petkov <bp@alien8.de> Analyzed-by: Peter Zijlstra <peterz@infradead.org> Cc: Julien Thierry <julien.thierry@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: <stable@vger.kernel.org> Fixes: 9dff0aa95a32 ("perf/core: Don't WARN() for impossible ring-buffer sizes") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@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);
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