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author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-08-17 06:15:16 (GMT) |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-09-27 12:39:24 (GMT) |
commit | de4360dd3519629fc0aabe6e87843038b84d75e3 (patch) | |
tree | a3c4fa6a092a5bbd036af1744712f236bb55b8da /net | |
parent | 536ab630f4db25fdfe7c46c027686ecad12150e7 (diff) | |
download | linux-de4360dd3519629fc0aabe6e87843038b84d75e3.tar.xz |
s390/mm: fix race on mm->context.flush_mm
commit 60f07c8ec5fae06c23e9fd7bab67dabce92b3414 upstream.
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.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
0 files changed, 0 insertions, 0 deletions