Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:
 "Two kernel side fixes: a kprobes fix and a perf_remove_from_context()
  fix (which does not yet fix the migration bug which is WIP)"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix a race condition in perf_remove_from_context()
  kprobes/x86: Free 'optinsn' cache when range check fails

2 files changed, 13 insertions, 1 deletions

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index f304773285ae..f1314d0bcf0a 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -338,8 +338,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
          * a relative jump.
          */
         rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
-        if (abs(rel) > 0x7fffffff)
+        if (abs(rel) > 0x7fffffff) {
+                __arch_remove_optimized_kprobe(op, 0);
                 return -ERANGE;
+        }
 
         buf = (u8 *)op->optinsn.insn;
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f9c1ed002dbc..d640a8b4dcbc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1524,6 +1524,11 @@ retry:
          */
         if (ctx->is_active) {
                 raw_spin_unlock_irq(&ctx->lock);
+                /*
+                 * Reload the task pointer, it might have been changed by
+                 * a concurrent perf_event_context_sched_out().
+                 */
+                task = ctx->task;
                 goto retry;
         }
 
@@ -1967,6 +1972,11 @@ retry:
          */
         if (ctx->is_active) {
                 raw_spin_unlock_irq(&ctx->lock);
+                /*
+                 * Reload the task pointer, it might have been changed by
+                 * a concurrent perf_event_context_sched_out().
+                 */
+                task = ctx->task;
                 goto retry;
         }