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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@kernel.org>
Link: https://lore.kernel.org/r/20250714-arm64-gcs-release-task-v2-1-8a83cadfc846@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Brown 2025-07-14 12:21:27 +01:00 committed by Will Deacon
parent 344b658047
commit 75fdf823f9
2 changed files with 0 additions and 7 deletions
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1
arch/arm64/kernel/process.c
View File

@ -339,7 +339,6 @@ 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)

6
arch/arm64/mm/gcs.c
View File

@ -157,12 +157,6 @@ void gcs_free(struct task_struct *task)
if (!system_supports_gcs())
return;
/*
* When fork() with CLONE_VM fails, the child (tsk) already
* has a GCS allocated, and exit_thread() calls this function
* to free it. In this case the parent (current) and the
* child share the same mm struct.
*/
if (!task->mm || task->mm != current->mm)
return;