Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'sched_urgent_for_v6.9_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Borislav Petkov:
- Add a missing memory barrier in the concurrency ID mm switching
* tag 'sched_urgent_for_v6.9_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Add missing memory barrier in switch_mm_cid
+25
-6
+3
arch/x86/include/asm/barrier.h
+3
arch/x86/include/asm/barrier.h
···
79
79
#define __smp_mb__before_atomic() do { } while (0)
80
80
#define __smp_mb__after_atomic() do { } while (0)
81
81
82
+
/* Writing to CR3 provides a full memory barrier in switch_mm(). */
83
+
#define smp_mb__after_switch_mm() do { } while (0)
84
+
82
85
#include <asm-generic/barrier.h>
83
86
84
87
#endif /* _ASM_X86_BARRIER_H */
+8
include/asm-generic/barrier.h
+8
include/asm-generic/barrier.h
···
294
294
#define io_stop_wc() do { } while (0)
295
295
#endif
296
296
297
+
/*
298
+
* Architectures that guarantee an implicit smp_mb() in switch_mm()
299
+
* can override smp_mb__after_switch_mm.
300
+
*/
301
+
#ifndef smp_mb__after_switch_mm
302
+
# define smp_mb__after_switch_mm() smp_mb()
303
+
#endif
304
+
297
305
#endif /* !__ASSEMBLY__ */
298
306
#endif /* __ASM_GENERIC_BARRIER_H */
+14
-6
kernel/sched/sched.h
+14
-6
kernel/sched/sched.h
···
79
79
# include <asm/paravirt_api_clock.h>
80
80
#endif
81
81
82
+
#include <asm/barrier.h>
83
+
82
84
#include "cpupri.h"
83
85
#include "cpudeadline.h"
84
86
···
3447
3445
* between rq->curr store and load of {prev,next}->mm->pcpu_cid[cpu].
3448
3446
* Provide it here.
3449
3447
*/
3450
-
if (!prev->mm) // from kernel
3448
+
if (!prev->mm) { // from kernel
3451
3449
smp_mb();
3452
-
/*
3453
-
* user -> user transition guarantees a memory barrier through
3454
-
* switch_mm() when current->mm changes. If current->mm is
3455
-
* unchanged, no barrier is needed.
3456
-
*/
3450
+
} else { // from user
3451
+
/*
3452
+
* user->user transition relies on an implicit
3453
+
* memory barrier in switch_mm() when
3454
+
* current->mm changes. If the architecture
3455
+
* switch_mm() does not have an implicit memory
3456
+
* barrier, it is emitted here. If current->mm
3457
+
* is unchanged, no barrier is needed.
3458
+
*/
3459
+
smp_mb__after_switch_mm();
3460
+
}
3457
3461
}
3458
3462
if (prev->mm_cid_active) {
3459
3463
mm_cid_snapshot_time(rq, prev->mm);