From 721bb7a129771f0ff9cef1dd5abfc106ef65feba Mon Sep 17 00:00:00 2001 From: Magnus Lindholm Date: Sat, 10 Oct 2026 16:24:33 +0200 Subject: [PATCH] alpha: invalidate the local context in flush_tlb_mm() flush_tlb_mm() has the same caller-CPU omission that was fixed in flush_tlb_page(): when the target mm is not the calling CPU's active_mm nothing happens locally, and smp_call_function() handles only the other CPUs, so this CPU may later reuse the old ASN together with the translations it still holds. The active_mm test itself is left alone here. That path calls flush_tlb_current(), which loads a fresh context through __load_new_mm_context() rather than issuing a targeted tbi() against whatever ASN happens to be loaded, so it does not depend on which context is current. The uniprocessor implementation in asm/tlbflush.h already has the missing branch. Counted over a fork-heavy run, flush_tlb_mm() was entered with the mm not this CPU's active_mm 2934 times, and 632 times while otherwise idle. The proposed Alpha hugetlb support routes hugetlb invalidations through flush_tlb_range(), which calls this function. Unmapping or migrating a hugetlb folio from another context will also need this local invalidate. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Matt Turner Signed-off-by: Magnus Lindholm Link: https://lore.kernel.org/r/20261010142533.974797-8-linmag7@gmail.com Signed-off-by: Magnus Lindholm --- 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 a5a42ae4a7d8..988e397b0b8a 100644 --- a/arch/alpha/kernel/smp.c +++ b/arch/alpha/kernel/smp.c @@ -649,6 +649,9 @@ flush_tlb_mm(struct mm_struct *mm) preempt_enable(); return; } + } else { + /* smp_call_function() does not call back into this CPU. */ + flush_tlb_other(mm); } smp_call_function(ipi_flush_tlb_mm, mm, 1);