diff options
| author | Adrian Hunter <adrian.hunter@intel.com> | 2024-06-24 23:11:00 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-07-04 16:00:23 +0200 |
| commit | 43deb76b19663a96ec2189d8f4eb9a9dc2d7623f (patch) | |
| tree | 7eeecacf11ab99771efdcb7e15219b909e43bdb4 /kernel/events | |
| parent | dbc48c8f41c208082cfa95e973560134489e3309 (diff) | |
perf: Fix default aux_watermark calculation
The default aux_watermark is half the AUX area buffer size. In general,
on a 64-bit architecture, the AUX area buffer size could be a bigger than
fits in a 32-bit type, but the calculation does not allow for that
possibility.
However the aux_watermark value is recorded in a u32, so should not be
more than U32_MAX either.
Fix by doing the calculation in a correctly sized type, and limiting the
result to U32_MAX.
Fixes: d68e6799a5c8 ("perf: Cap allocation order at aux_watermark")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240624201101.60186-7-adrian.hunter@intel.com
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/ring_buffer.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 4013408ce012..485cf0a66631 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -688,7 +688,9 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, * max_order, to aid PMU drivers in double buffering. */ if (!watermark) - watermark = nr_pages << (PAGE_SHIFT - 1); + watermark = min_t(unsigned long, + U32_MAX, + (unsigned long)nr_pages << (PAGE_SHIFT - 1)); /* * Use aux_watermark as the basis for chunking to |