linux-kernel - [PATCH v2 2/4] x86/mm: Fix wrong judgement in allocate_global

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Message-Id: <7351bac66842ba58a9da011ea2ad45fb26079638.1768900340.git.houwenlong.hwl@antgroup.com>
Date: Tue, 20 Jan 2026 21:44:28 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: linux-kernel@...r.kernel.org
Cc: Hou Wenlong <houwenlong.hwl@...group.com>,
	Rik van Riel <riel@...riel.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 2/4] x86/mm: Fix wrong judgement in allocate_global_asid()

In allocate_global_asid(), 'global_asid_available' cannot be zero, as it
has already been checked in use_global_asid(). The wrong judgment could
result in the invalid ASID 'MAX_ASID_AVAILABLE' being allocated,
triggering the warning in kern_pcid(). Therefore, remove the check for
'global_asid_available', since when the allocation reaches
'MAX_ASID_AVAILABLE', it must return regardless of the value of
'global_asid_available'.

Fixes: d504d1247e36 ("x86/mm: Add global ASID allocation helper functions")
Reviewed-by: Rik van Riel <riel@...riel.com>
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 42b025e2f825..a1e217a382d1 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -326,7 +326,7 @@ static u16 allocate_global_asid(void)
 
 	asid = find_next_zero_bit(global_asid_used, MAX_ASID_AVAILABLE, last_global_asid);
 
-	if (asid >= MAX_ASID_AVAILABLE && !global_asid_available) {
+	if (asid >= MAX_ASID_AVAILABLE) {
 		/* This should never happen. */
 		VM_WARN_ONCE(1, "Unable to allocate global ASID despite %d available\n",
 				global_asid_available);
-- 
2.31.1