linux-kernel - [PATCH v2 1/4] x86/mm: Correct the actual size of available global ASID range

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Message-Id: <30c6abf8d2a246cde256f943adaa7251ae09b2df.1768900340.git.houwenlong.hwl@antgroup.com>
Date: Tue, 20 Jan 2026 21:44:27 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: linux-kernel@...r.kernel.org
Cc: Hou Wenlong <houwenlong.hwl@...group.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v2 1/4] x86/mm: Correct the actual size of available global ASID range

As noted in the comment, the available ASID range for global ASID
allocation is '[TLB_NR_DYN_ASIDS, MAX_ASID_AVAILABLE-1]', which is a
close interval. The size of bitmap is defined as 'MAX_ASID_AVAILABLE',
so the actual available size should be
'(MAX_ASID_AVAILABLE-1) - TLB_NR_DYN_ASIDS + 1'; otherwise, one ASID will
leak.

Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/mm/tlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 621e09d049cb..42b025e2f825 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -286,7 +286,7 @@ static DEFINE_RAW_SPINLOCK(global_asid_lock);
 static u16 last_global_asid = MAX_ASID_AVAILABLE;
 static DECLARE_BITMAP(global_asid_used, MAX_ASID_AVAILABLE);
 static DECLARE_BITMAP(global_asid_freed, MAX_ASID_AVAILABLE);
-static int global_asid_available = MAX_ASID_AVAILABLE - TLB_NR_DYN_ASIDS - 1;
+static int global_asid_available = MAX_ASID_AVAILABLE - TLB_NR_DYN_ASIDS;
 
 /*
  * When the search for a free ASID in the global ASID space reaches
-- 
2.31.1