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author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-08-17 09:15:16 +0300 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-09-06 10:24:42 +0300 |
commit | 60f07c8ec5fae06c23e9fd7bab67dabce92b3414 (patch) | |
tree | 3c189bb7d158caba68c36b467603f94b243eea8f /arch/s390/include/asm/mmu.h | |
parent | b3e5dc45fd1ec2aa1de6b80008f9295eb17e0659 (diff) | |
download | linux-60f07c8ec5fae06c23e9fd7bab67dabce92b3414.tar.xz |
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.h')
-rw-r--r-- | arch/s390/include/asm/mmu.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h index bd6f30304518..3525fe6e7e4c 100644 --- a/arch/s390/include/asm/mmu.h +++ b/arch/s390/include/asm/mmu.h @@ -5,6 +5,7 @@ #include <linux/errno.h> typedef struct { + spinlock_t lock; cpumask_t cpu_attach_mask; atomic_t flush_count; unsigned int flush_mm; @@ -27,6 +28,7 @@ typedef struct { } mm_context_t; #define INIT_MM_CONTEXT(name) \ + .context.lock = __SPIN_LOCK_UNLOCKED(name.context.lock), \ .context.pgtable_lock = \ __SPIN_LOCK_UNLOCKED(name.context.pgtable_lock), \ .context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \ |