From: Rik van Riel <riel@surriel.com>
Date: Thu, 14 Nov 2024 15:26:17 +0000 (-0500)
Subject: x86/mm/tlb: Add tracepoint for TLB flush IPI to stale CPU
X-Git-Tag: v6.14-rc1~20^2~6
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2815a56e4b7252a836969f5674ee356ea1ce482c;p=thirdparty%2Fkernel%2Flinux.git

x86/mm/tlb: Add tracepoint for TLB flush IPI to stale CPU

Add a tracepoint when we send a TLB flush IPI to a CPU that used
to be in the mm_cpumask, but isn't any more.

Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241114152723.1294686-3-riel@surriel.com
---

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index cc4e57ae690f5..1aac4fa90d3d8 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -760,6 +760,7 @@ static void flush_tlb_func(void *info)
 		/* 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;
 		}
 	}
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6e3bdf8e38bca..6b6f05404304c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1335,6 +1335,7 @@ enum tlb_flush_reason {
 	TLB_LOCAL_SHOOTDOWN,
 	TLB_LOCAL_MM_SHOOTDOWN,
 	TLB_REMOTE_SEND_IPI,
+	TLB_REMOTE_WRONG_CPU,
 	NR_TLB_FLUSH_REASONS,
 };