linux-kernel - [PATCH] arm64/gcs: Don't call gcs_free() when releasing task

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Message-Id: <20250625-arm64-gcs-release-task-v1-1-54cbdc2db416@kernel.org>
Date: Wed, 25 Jun 2025 19:56:34 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Mark Brown <broonie@...nel.org>
Subject: [PATCH] arm64/gcs: Don't call gcs_free() when releasing
 task_struct

Currently we call gcs_free() when releasing task_struct but this is
redundant, it attempts to deallocate any kernel managed userspace GCS
which should no longer be relevant and resets values in the struct we're
in the process of freeing.

By the time arch_release_task_struct() is called the mm will have been
disassociated from the task so the check for a mm in gcs_free() will
always be false, for threads that are exiting leaving the mm active
deactivate_mm() will have been called previously and freed any kernel
managed GCS.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/kernel/process.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 5954cec19660..5dcfab9ce012 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -341,7 +341,6 @@ void flush_thread(void)
 void arch_release_task_struct(struct task_struct *tsk)
 {
 	fpsimd_release_task(tsk);
-	gcs_free(tsk);
 }

 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)

---
base-commit: 86731a2a651e58953fc949573895f2fa6d456841
change-id: 20250610-arm64-gcs-release-task-307db60fa1b4

Best regards,
--  
Mark Brown <broonie@...nel.org>