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SubjectRe: [PATCH 4/4] mm/vmalloc: remove vfree_atomic()
On Thu 30-03-17 13:27:19, Andrey Ryabinin wrote:
> vfree() can be used in any atomic context and there is no
> vfree_atomic() callers left, so let's remove it.
>
> This reverts commit bf22e37a6413 ("mm: add vfree_atomic()")
>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

the idea was nice but reality hits the fan and we learn that this just
doesn't work...
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> include/linux/vmalloc.h | 1 -
> mm/vmalloc.c | 40 +++++-----------------------------------
> 2 files changed, 5 insertions(+), 36 deletions(-)
>
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 46991ad..b4f044f 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -83,7 +83,6 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
> extern void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags);
>
> extern void vfree(const void *addr);
> -extern void vfree_atomic(const void *addr);
>
> extern void *vmap(struct page **pages, unsigned int count,
> unsigned long flags, pgprot_t prot);
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ea1b4ab..b77337a 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1534,38 +1534,6 @@ static void __vunmap(const void *addr, int deallocate_pages)
> return;
> }
>
> -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
> - * nother 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
> - *
> - * This one is just like vfree() but can be called in any atomic context
> - * except NMIs.
> - */
> -void vfree_atomic(const void *addr)
> -{
> - BUG_ON(in_nmi());
> -
> - kmemleak_free(addr);
> -
> - if (!addr)
> - return;
> - __vfree_deferred(addr);
> -}
> -
> /**
> * vfree - release memory allocated by vmalloc()
> * @addr: memory base address
> @@ -1588,9 +1556,11 @@ void vfree(const void *addr)
>
> if (!addr)
> return;
> - if (unlikely(in_interrupt()))
> - __vfree_deferred(addr);
> - else
> + if (unlikely(in_interrupt())) {
> + struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred);
> + if (llist_add((struct llist_node *)addr, &p->list))
> + schedule_work(&p->wq);
> + } else
> __vunmap(addr, 1);
> }
> EXPORT_SYMBOL(vfree);
> --
> 2.10.2
>
> --
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--
Michal Hocko
SUSE Labs

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