[RFC 05/10] x86/mm: Change the leave_mm() condition for local TLB flushes

Andy Lutomirski
2017-05-07T22:06:24Z

On a remote TLB flush, we leave_mm() if we're TLBSTATE_LAZY. For a
local flush_tlb_mm_range(), we leave_mm() if !current->mm. These
are approximately the same condition -- the scheduler sets lazy TLB
mode when switching to a thread with no mm.

I'm about to merge the local and remote flush code, but for ease of
verifying and bisecting the patch, I want the local and remote flush
behavior to match first. This patch changes the local code to match
the remote code.

Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/mm/tlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 776469cc54e0..3143c9a180e5 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -311,7 +311,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
goto out;
}

- if (!current->mm) {
+ if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
leave_mm(smp_processor_id());

/* Synchronize with switch_mm. */
--
2.9.3