[PATCH v4 4/8] alpha: invalidate the local context in flush_tlb_page()

[Magnus Lindholm]

When the target mm is not the calling CPU's active_mm, flush_tlb_page()
does nothing locally, and smp_call_function() reaches only the other CPUs.
This CPU may still
hold translations for the mm and can later reuse the old ASN together with
them.

Add the missing else branch. flush_tlb_other() clears mm->context[cpu] so
a fresh ASN is taken at the next switch. Add this before changing the
current->active_mm test to current->mm: that change will also send lazy
callers here, so their local invalidate must already be in place.

The uniprocessor implementations of flush_tlb_mm() and
flush_icache_user_page() in asm/tlbflush.h and asm/cacheflush.h already
contain exactly this branch.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Matt Turner <mattst88@xxxxxxxxx>
Signed-off-by: Magnus Lindholm <linmag7@xxxxxxxxx>
Message-ID: <20260923074903.862898-5-linmag7@xxxxxxxxx>
---
 arch/alpha/kernel/smp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 1ad448105201..e4ba0aab8a66 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -697,6 +697,9 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 			preempt_enable();
 			return;
 		}
+	} else {
+		/* smp_call_function() does not call back into this CPU.  */
+		flush_tlb_other(mm);
 	}
 
 	data.vma = vma;
-- 
2.43.0