x86, bts: use atomic memory allocation

Ds_request_bts() needs to allocate memory. It uses GFP_KERNEL.

Hw-branch-tracer calls ds_request_bts() within on_each_cpu().

Use atomic memory allocation to allow it to be used in that context.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090318192700.A6038@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 17 insertions, 4 deletions

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 5fd53333c1df..b1d6e1f502fa 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -255,8 +255,13 @@ static inline struct ds_context *ds_get_context(struct task_struct *task)
         struct ds_context *new_context = NULL;
         unsigned long irq;
 
-        /* Chances are small that we already have a context. */
-        new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
+        /*
+         * Chances are small that we already have a context.
+         *
+         * Contexts for per-cpu tracing are allocated using
+         * smp_call_function(). We must not sleep.
+         */
+        new_context = kzalloc(sizeof(*new_context), GFP_ATOMIC);
         if (!new_context)
                 return NULL;
 
@@ -662,8 +667,12 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
         if (ovfl)
                 goto out;
 
+        /*
+         * Per-cpu tracing is typically requested using smp_call_function().
+         * We must not sleep.
+         */
         error = -ENOMEM;
-        tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
+        tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
         if (!tracer)
                 goto out;
         tracer->ovfl = ovfl;
@@ -722,8 +731,12 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
         if (ovfl)
                 goto out;
 
+        /*
+         * Per-cpu tracing is typically requested using smp_call_function().
+         * We must not sleep.
+         */
         error = -ENOMEM;
-        tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
+        tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
         if (!tracer)
                 goto out;
         tracer->ovfl = ovfl;