mm/tlb: Remove tlb_remove_table() non-concurrent condition
authorPeter Zijlstra <peterz@infradead.org>
Wed, 22 Aug 2018 15:30:14 +0000 (17:30 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 9 Sep 2018 17:55:59 +0000 (19:55 +0200)
commit7cf82f3b7a7710dc29fc90ce83bee8a1ea7ff6fb
treeb5d83ca97d10d7f292128d366aab0d15a778c2f4
parentddcb92700552eeedea717dcca9b16b0a99d26679
mm/tlb: Remove tlb_remove_table() non-concurrent condition

commit a6f572084fbee8b30f91465f4a085d7a90901c57 upstream.

Will noted that only checking mm_users is incorrect; we should also
check mm_count in order to cover CPUs that have a lazy reference to
this mm (and could do speculative TLB operations).

If removing this turns out to be a performance issue, we can
re-instate a more complete check, but in tlb_table_flush() eliding the
call_rcu_sched().

Fixes: 267239116987 ("mm, powerpc: move the RCU page-table freeing into generic code")
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm/memory.c