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| author | Thomas Gleixner <tglx@linutronix.de> | 2020-11-18 20:48:43 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-11-24 14:42:09 +0100 |
| commit | 5fbda3ecd14a5343644979c98d6eb65b7e7de9d8 (patch) | |
| tree | 6bd9a839faabd90f349b3204c14b9728f99cba2e /include/linux/highmem-internal.h | |
| parent | 14df32670291588036a498051a54cd8462d7f611 (diff) | |
| download | lwn-5fbda3ecd14a5343644979c98d6eb65b7e7de9d8.tar.gz lwn-5fbda3ecd14a5343644979c98d6eb65b7e7de9d8.zip | |
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 'include/linux/highmem-internal.h')
| -rw-r--r-- | include/linux/highmem-internal.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h index 6ceed907b14e..c5a22177db85 100644 --- a/include/linux/highmem-internal.h +++ b/include/linux/highmem-internal.h @@ -9,6 +9,16 @@ void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot); void *__kmap_local_page_prot(struct page *page, pgprot_t prot); void kunmap_local_indexed(void *vaddr); +void kmap_local_fork(struct task_struct *tsk); +void __kmap_local_sched_out(void); +void __kmap_local_sched_in(void); +static inline void kmap_assert_nomap(void) +{ + DEBUG_LOCKS_WARN_ON(current->kmap_ctrl.idx); +} +#else +static inline void kmap_local_fork(struct task_struct *tsk) { } +static inline void kmap_assert_nomap(void) { } #endif #ifdef CONFIG_HIGHMEM |