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authorPeter Zijlstra <peterz@infradead.org>2018-08-22 17:30:14 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-09 20:04:34 +0200
commit70201a4e368833c15625d8dc32fd9c0286a12b58 (patch)
tree5c2b2ec7cbf35248b7c2a45a69f0b26c3373ec26 /mm/memory.c
parent2f04971a962949099881dfc7be23392ad14aa8c9 (diff)
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>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c9
1 files changed, 0 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 42db644f5ec4..5aee9ec8b8c6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -361,15 +361,6 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
struct mmu_table_batch **batch = &tlb->batch;
- /*
- * When there's less then two users of this mm there cannot be a
- * concurrent page-table walk.
- */
- if (atomic_read(&tlb->mm->mm_users) < 2) {
- __tlb_remove_table(table);
- return;
- }
-
if (*batch == NULL) {
*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
if (*batch == NULL) {