[tip: x86/mm] x86/mm: Factor out flush_tlb_info initialization

["tip-bot2 for Chuyi Zhou" <tip-bot2@linutronix.de>]

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

Commit-ID:     33c179b5020554722bcb4c5a3ff565192ac53f54
Gitweb:        https://git.kernel.org/tip/33c179b5020554722bcb4c5a3ff565192ac53f54
Author:        Chuyi Zhou <zhouchuyi@bytedance.com>
AuthorDate:    Thu, 09 Jul 2026 20:29:29 +08:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Thu, 23 Jul 2026 12:30:31 +02:00

x86/mm: Factor out flush_tlb_info initialization

get_flush_tlb_info() has two responsibilities: it reserves the per-CPU
flush_tlb_info storage and it initializes the fields that describe the
flush operation. The per-CPU storage also carries the DEBUG_VM
reentrancy check and the matching put_flush_tlb_info() lifetime rules.

Moving flush_tlb_info back to caller-provided storage requires the same
field initialization without tying the caller to the per-CPU object.
Leaving the field setup embedded in get_flush_tlb_info() would either
keep those callers tied to the per-CPU object or duplicate the
initialization logic.

Split the field setup into init_flush_tlb_info(). Keep the per-CPU
storage selection, DEBUG_VM reentrancy check and put_flush_tlb_info()
lifetime rules in get_flush_tlb_info().

No functional change intended.

Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260709122933.4021501-11-zhouchuyi@bytedance.com
---
 arch/x86/mm/tlb.c | 40 +++++++++++++++++++++++-----------------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 1023aca..7f48342 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1379,29 +1379,18 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct flush_tlb_info, flush_tlb_info);
 static DEFINE_PER_CPU(unsigned int, flush_tlb_info_idx);
 #endif
 
-static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
-			unsigned long start, unsigned long end,
-			unsigned int stride_shift, bool freed_tables,
-			u64 new_tlb_gen)
+static void init_flush_tlb_info(struct flush_tlb_info *info, struct mm_struct *mm,
+				unsigned long start, unsigned long end,
+				unsigned int stride_shift, bool freed_tables,
+				u64 new_tlb_gen)
 {
-	struct flush_tlb_info *info = this_cpu_ptr(&flush_tlb_info);
-
-#ifdef CONFIG_DEBUG_VM
-	/*
-	 * Ensure that the following code is non-reentrant and flush_tlb_info
-	 * is not overwritten. This means no TLB flushing is initiated by
-	 * interrupt handlers and machine-check exception handlers.
-	 */
-	BUG_ON(this_cpu_inc_return(flush_tlb_info_idx) != 1);
-#endif
-
 	/*
 	 * If the number of flushes is so large that a full flush
 	 * would be faster, do a full flush.
 	 */
 	if ((end - start) >> stride_shift > tlb_single_page_flush_ceiling) {
-		start = 0;
-		end = TLB_FLUSH_ALL;
+		start	= 0;
+		end	= TLB_FLUSH_ALL;
 	}
 
 	info->start		= start;
@@ -1412,7 +1401,24 @@ static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	info->new_tlb_gen	= new_tlb_gen;
 	info->initiating_cpu	= smp_processor_id();
 	info->trim_cpumask	= 0;
+}
+
+static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm, unsigned long start,
+						 unsigned long end, unsigned int stride_shift,
+						 bool freed_tables, u64 new_tlb_gen)
+{
+	struct flush_tlb_info *info = this_cpu_ptr(&flush_tlb_info);
+
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * Ensure that the following code is non-reentrant and flush_tlb_info
+	 * is not overwritten. This means no TLB flushing is initiated by
+	 * interrupt handlers and machine-check exception handlers.
+	 */
+	BUG_ON(this_cpu_inc_return(flush_tlb_info_idx) != 1);
+#endif
 
+	init_flush_tlb_info(info, mm, start, end, stride_shift, freed_tables, new_tlb_gen);
 	return info;
 }