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

From: tip-bot2 for Rik van Riel
Date: Tue Nov 19 2024 - 06:27:47 EST


The following commit has been merged into the x86/mm branch of tip:

Commit-ID: 2815a56e4b7252a836969f5674ee356ea1ce482c
Gitweb: https://git.kernel.org/tip/2815a56e4b7252a836969f5674ee356ea1ce482c
Author: Rik van Riel <riel@xxxxxxxxxxx>
AuthorDate: Thu, 14 Nov 2024 10:26:17 -05:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 19 Nov 2024 12:02:46 +01:00

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@xxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20241114152723.1294686-3-riel@xxxxxxxxxxx
---
arch/x86/mm/tlb.c | 1 +
include/linux/mm_types.h | 1 +
2 files changed, 2 insertions(+)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index cc4e57a..1aac4fa 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 6e3bdf8..6b6f054 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,
};