From: Anton Blanchard <anton@samba.org>
When trawling though code I noticed something that could be dodgy, if
cpu_vm_mask ever got out of sync all manner of weird things can happen.
Im not sure if there is a bug here yet, youd have to fork (which zeros
cpu_vm_mask) and somehow reuse the same mm (so the prev == next is true).
Anyway heres the patch, Ill probably play it safe and merge it.
---
25-akpm/include/asm-ppc64/mmu_context.h | 3 ++-
1 files changed, 2 insertions(+), 1 deletion(-)
diff -puN include/asm-ppc64/mmu_context.h~ppc64-cpu_vm_mask-fix include/asm-ppc64/mmu_context.h
--- 25/include/asm-ppc64/mmu_context.h~ppc64-cpu_vm_mask-fix Tue Feb 3 13:18:12 2004
+++ 25-akpm/include/asm-ppc64/mmu_context.h Tue Feb 3 13:18:12 2004
@@ -156,6 +156,8 @@ static inline void switch_mm(struct mm_s
: : );
#endif /* CONFIG_ALTIVEC */
+ cpu_set(smp_processor_id(), next->cpu_vm_mask);
+
/* No need to flush userspace segments if the mm doesnt change */
if (prev == next)
return;
@@ -164,7 +166,6 @@ static inline void switch_mm(struct mm_s
flush_slb(tsk, next);
else
flush_stab(tsk, next);
- cpu_set(smp_processor_id(), next->cpu_vm_mask);
}
#define deactivate_mm(tsk,mm) do { } while (0)
_