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authorThomas Gleixner <tglx@linutronix.de>2020-11-18 20:48:43 +0100
committerThomas Gleixner <tglx@linutronix.de>2020-11-24 14:42:09 +0100
commit5fbda3ecd14a5343644979c98d6eb65b7e7de9d8 (patch)
tree6bd9a839faabd90f349b3204c14b9728f99cba2e /kernel/fork.c
parent14df32670291588036a498051a54cd8462d7f611 (diff)
downloadlinux-5fbda3ecd14a5343644979c98d6eb65b7e7de9d8.tar.bz2
sched: highmem: Store local kmaps in task struct
Instead of storing the map per CPU provide and use per task storage. That prepares for local kmaps which are preemptible. The context switch code is preparatory and not yet in use because kmap_atomic() runs with preemption disabled. Will be made usable in the next step. The context switch logic is safe even when an interrupt happens after clearing or before restoring the kmaps. The kmap index in task struct is not modified so any nesting kmap in an interrupt will use unused indices and on return the counter is the same as before. Also add an assert into the return to user space code. Going back to user space with an active kmap local is a nono. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20201118204007.372935758@linutronix.de
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 32083db7a2a2..17dcd1817799 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -930,6 +930,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
account_kernel_stack(tsk, 1);
kcov_task_init(tsk);
+ kmap_local_fork(tsk);
#ifdef CONFIG_FAULT_INJECTION
tsk->fail_nth = 0;