This originated from s390 which does something similar and would allow s390 to use the generic TLB flushing code. The idea is to flush the mm wide cache and tlb a priory and not bother with multiple flushes if the batching isn't large enough. This can be safely done since there cannot be any concurrency on this mm, its either after the process died (exit) or in the middle of execve where the thread switched to the new mm. Signed-off-by: Peter Zijlstra --- include/asm-generic/tlb.h | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) Index: linux-2.6/include/asm-generic/tlb.h =================================================================== --- linux-2.6.orig/include/asm-generic/tlb.h +++ linux-2.6/include/asm-generic/tlb.h @@ -149,6 +149,11 @@ tlb_gather_mmu(struct mmu_gather *tlb, s #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb->batch = NULL; #endif + + if (fullmm) { + flush_cache_mm(mm); + flush_tlb_mm(mm); + } } static inline void @@ -156,13 +161,15 @@ tlb_flush_mmu(struct mmu_gather *tlb) { struct mmu_gather_batch *batch; - if (!tlb->need_flush) - return; - tlb->need_flush = 0; - tlb_flush(tlb); + if (!tlb->fullmm && tlb->need_flush) { + tlb->need_flush = 0; + tlb_flush(tlb); + } + #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb_table_flush(tlb); #endif + if (tlb_fast_mode(tlb)) return;