On Thu, Jan 19, 2023 at 11:02:19AM +0100, Christoph Hellwig wrote:
> Fold __vfree_deferred into vfree_atomic, and call vfree_atomic early on
> from vfree if called from interrupt context so that the extra low-level
> helper can be avoided.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> mm/vmalloc.c | 43 +++++++++++++++++--------------------------
> 1 file changed, 17 insertions(+), 26 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index b989828b45109a..fafb6227f4428f 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2769,20 +2769,6 @@ static void __vunmap(const void *addr, int deallocate_pages)
> kfree(area);
> }
>
> -static inline void __vfree_deferred(const void *addr)
> -{
> - /*
> - * Use raw_cpu_ptr() because this can be called from preemptible
> - * context. Preemption is absolutely fine here, because the llist_add()
> - * implementation is lockless, so it works even if we are adding to
> - * another cpu's list. schedule_work() should be fine with this too.
> - */
> - struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);
> -
> - if (llist_add((struct llist_node *)addr, &p->list))
> - schedule_work(&p->wq);
> -}
> -
> /**
> * vfree_atomic - release memory allocated by vmalloc()
> * @addr: memory base address
> @@ -2792,13 +2778,19 @@ static inline void __vfree_deferred(const void *addr)
> */
> void vfree_atomic(const void *addr)
> {
> - BUG_ON(in_nmi());
> + struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);
>
> + BUG_ON(in_nmi());
> kmemleak_free(addr);
>
> - if (!addr)
> - return;
> - __vfree_deferred(addr);
> + /*
> + * Use raw_cpu_ptr() because this can be called from preemptible
> + * context. Preemption is absolutely fine here, because the llist_add()
> + * implementation is lockless, so it works even if we are adding to
> + * another cpu's list. schedule_work() should be fine with this too.
> + */
> + if (addr && llist_add((struct llist_node *)addr, &p->list))
> + schedule_work(&p->wq);
> }
>
> /**
> @@ -2820,17 +2812,16 @@ void vfree_atomic(const void *addr)
> */
> void vfree(const void *addr)
> {
> - BUG_ON(in_nmi());
> + if (unlikely(in_interrupt())) {
> + vfree_atomic(addr);
> + return;
> + }
>
> + BUG_ON(in_nmi());
> kmemleak_free(addr);
> + might_sleep();
>
> - might_sleep_if(!in_interrupt());
> -
> - if (!addr)
> - return;
> - if (unlikely(in_interrupt()))
> - __vfree_deferred(addr);
> - else
> + if (addr)
> __vunmap(addr, 1);
> }
> EXPORT_SYMBOL(vfree);
> --
> 2.39.0
>
Such folding makes sense to me.
Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
--
Uladzislau Rezki
