task_work_add(RWA_RESUME) isn't NMI-safe, use TWA_NMI_CURRENT when
used from NMI context.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/unwind/deferred.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/kernel/unwind/deferred.c
+++ b/kernel/unwind/deferred.c
@@ -231,6 +231,7 @@ void unwind_deferred_task_exit(struct ta
int unwind_deferred_request(struct unwind_work *work, u64 *cookie)
{
struct unwind_task_info *info = ¤t->unwind_info;
+ int twa_mode = TWA_RESUME;
unsigned long old, bits;
unsigned long bit;
int ret;
@@ -246,8 +247,11 @@ int unwind_deferred_request(struct unwin
* Trigger a warning to make it obvious that an architecture
* is using this in NMI when it should not be.
*/
- if (WARN_ON_ONCE(!CAN_USE_IN_NMI && in_nmi()))
- return -EINVAL;
+ if (in_nmi()) {
+ if (WARN_ON_ONCE(!CAN_USE_IN_NMI))
+ return -EINVAL;
+ twa_mode = TWA_NMI_CURRENT;
+ }
/* Do not allow cancelled works to request again */
bit = READ_ONCE(work->bit);
@@ -285,7 +289,7 @@ int unwind_deferred_request(struct unwin
}
/* The work has been claimed, now schedule it. */
- ret = task_work_add(current, &info->work, TWA_RESUME);
+ ret = task_work_add(current, &info->work, twa_mode);
if (WARN_ON_ONCE(ret))
WRITE_ONCE(info->unwind_mask, 0);