linux-kernel - Re: [PATCH v2 1/3] mm: vmalloc: Avoid of calling __find_vmap_area() twise in _

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Date:   Thu, 22 Dec 2022 15:41:29 +0100
From:   Uladzislau Rezki <urezki@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>
Subject: Re: [PATCH v2 1/3] mm: vmalloc: Avoid of calling __find_vmap_area()
 twise in __vunmap()

> A sorry.  I need more coffee, this is not the cover letter, but the
> patch that introduceѕ find_unlink_vmap_area.
> 
Sorry. I should post it with a cover latter to make it less confusing.

> > -	spin_lock(&vmap_area_lock);
> > -	unlink_va(va, &vmap_area_root);
> > -	spin_unlock(&vmap_area_lock);
> > +	if (!list_empty(&va->list)) {
> > +		spin_lock(&vmap_area_lock);
> > +		unlink_va(va, &vmap_area_root);
> > +		spin_unlock(&vmap_area_lock);
> > +	}
> 
> As mentioned before, I'd much rather move this into the callers.
> 
Agree. There is only one caller, it is the free_vmap_block().
Will fix in the v3.

> > +	va = find_unlink_vmap_area((unsigned long) addr);
> > +	return __remove_vm_area(va);
> 
> This can drop the va local variable now.
>
Do you mean like:

struct vm_struct *remove_vm_area(const void *addr)
{
    might_sleep();
    return __remove_vm_area(
        find_unlink_vmap_area((unsigned long) addr));
}

?

Thanks for review!

--
Uladzislau Rezki