From 953753db887f9d70f70f61d6ecbe5cf209107672 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Thu, 5 Dec 2024 10:46:30 -0500 Subject: [PATCH] x86/mm/tlb: Also remove local CPU from mm_cpumask if stale The code in flush_tlb_func() that removes a remote CPU from the cpumask if it is no longer running the target mm is also needed on the originating CPU of a TLB flush, now that CPUs are no longer cleared from the mm_cpumask at context switch time. Flushing the TLB when we are not running the target mm is harmless, because the CPU's tlb_gen only gets updated to match the mm_tlb_gen, but it does hit this warning: WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen); [ 210.343902][ T4668] WARNING: CPU: 38 PID: 4668 at arch/x86/mm/tlb.c:815 flush_tlb_func (arch/x86/mm/tlb.c:815) Removing both local and remote CPUs from the mm_cpumask when doing a flush for a not currently loaded mm avoids that warning. Reported-by: kernel test robot Tested-by: kernel test robot Signed-off-by: Rik van Riel Signed-off-by: Ingo Molnar Cc: Dave Hansen Cc: Mathieu Desnoyers Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Linus Torvalds Link: https://lore.kernel.org/r/20241205104630.755706ca@fangorn Closes: https://lore.kernel.org/oe-lkp/202412051551.690e9656-lkp@intel.com --- arch/x86/mm/tlb.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 1aac4fa90d3d..3c30817ec6a2 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -756,13 +756,13 @@ static void flush_tlb_func(void *info) if (!local) { inc_irq_stat(irq_tlb_count); count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED); + } - /* Can only happen on remote CPUs */ - if (f->mm && f->mm != loaded_mm) { - cpumask_clear_cpu(raw_smp_processor_id(), mm_cpumask(f->mm)); - trace_tlb_flush(TLB_REMOTE_WRONG_CPU, 0); - return; - } + /* The CPU was left in the mm_cpumask of the target mm. Clear it. */ + if (f->mm && f->mm != loaded_mm) { + cpumask_clear_cpu(raw_smp_processor_id(), mm_cpumask(f->mm)); + trace_tlb_flush(TLB_REMOTE_WRONG_CPU, 0); + return; } if (unlikely(loaded_mm == &init_mm))