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unwind: Fix unwind_deferred_request() vs NMI

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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>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://patch.msgid.link/20250924080119.005422353@infradead.org
This commit is contained in:
Peter Zijlstra
2025-09-22 15:47:56 +02:00
parent ae577ea0bc
commit a38a64712e
1 changed files with 7 additions and 3 deletions
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10
kernel/unwind/deferred.c
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@@ -231,6 +231,7 @@ void unwind_deferred_task_exit(struct task_struct *task)
int unwind_deferred_request(struct unwind_work *work, u64 *cookie)
{
struct unwind_task_info *info = &current->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 unwind_work *work, u64 *cookie)
* 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 unwind_work *work, u64 *cookie)
}
/* 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);