perf: Rebase max unprivileged mlock threshold on top of page size

Ensure we allow 512 kiB + 1 page for user control without
assuming a 4096 bytes page size.

Reported-by: Peter Zijlstra <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: <[email protected]>
LKML-Reference: <1301535209[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c75925c4d1e29a3296bed32a6f0eeb7e6c189c29..261690923ffb77d2060ac0a0dadeb4a716522917 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,8 +145,8 @@ static struct srcu_struct pmus_srcu;
  */
 int sysctl_perf_event_paranoid __read_mostly = 1;
 
-/* Minimum for 128 pages + 1 for the user control page */
-int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
 
 /*
  * max perf event sample rate