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author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-08-17 08:15:16 +0200 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-09-06 09:24:42 +0200 |
commit | 60f07c8ec5fae06c23e9fd7bab67dabce92b3414 (patch) | |
tree | 3c189bb7d158caba68c36b467603f94b243eea8f /arch/s390/include/asm/mmu_context.h | |
parent | b3e5dc45fd1ec2aa1de6b80008f9295eb17e0659 (diff) | |
download | op-kernel-dev-60f07c8ec5fae06c23e9fd7bab67dabce92b3414.zip op-kernel-dev-60f07c8ec5fae06c23e9fd7bab67dabce92b3414.tar.gz |
s390/mm: fix race on mm->context.flush_mm
The order in __tlb_flush_mm_lazy is to flush TLB first and then clear
the mm->context.flush_mm bit. This can lead to missed flushes as the
bit can be set anytime, the order needs to be the other way aronud.
But this leads to a different race, __tlb_flush_mm_lazy may be called
on two CPUs concurrently. If mm->context.flush_mm is cleared first then
another CPU can bypass __tlb_flush_mm_lazy although the first CPU has
not done the flush yet. In a virtualized environment the time until the
flush is finally completed can be arbitrarily long.
Add a spinlock to serialize __tlb_flush_mm_lazy and use the function
in finish_arch_post_lock_switch as well.
Cc: <stable@vger.kernel.org>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/mmu_context.h')
-rw-r--r-- | arch/s390/include/asm/mmu_context.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h index 8823e35..484efe8 100644 --- a/arch/s390/include/asm/mmu_context.h +++ b/arch/s390/include/asm/mmu_context.h @@ -17,6 +17,7 @@ static inline int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { + spin_lock_init(&mm->context.lock); spin_lock_init(&mm->context.pgtable_lock); INIT_LIST_HEAD(&mm->context.pgtable_list); spin_lock_init(&mm->context.gmap_lock); @@ -121,8 +122,7 @@ static inline void finish_arch_post_lock_switch(void) while (atomic_read(&mm->context.flush_count)) cpu_relax(); cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); - if (mm->context.flush_mm) - __tlb_flush_mm(mm); + __tlb_flush_mm_lazy(mm); preempt_enable(); } set_fs(current->thread.mm_segment); |