linux-kernel - Re: [PATCH 5/9] mm: vmalloc: Insert busy-VA per-cpu zone

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Message-ID: <ZGzVD7hkl5v3A2dO@pc636>
Date:   Tue, 23 May 2023 17:00:31 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Dave Chinner <david@...morbit.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 5/9] mm: vmalloc: Insert busy-VA per-cpu zone

On Mon, May 22, 2023 at 11:12:08PM -0700, Christoph Hellwig wrote:
> >  /* Look up the first VA which satisfies addr < va_end, NULL if none. */
> > -static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr)
> > +static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr, struct rb_root *root)
> 
> Please avoid the overly long line.
> 
Will fix it.

> > +	struct cpu_vmap_zone *z = addr_to_cvz(va->va_start);
> > +
> >  	/*
> >  	 * Remove from the busy tree/list.
> >  	 */
> > -	spin_lock(&vmap_area_lock);
> > -	unlink_va(va, &vmap_area_root);
> > -	spin_unlock(&vmap_area_lock);
> > +	fbl_lock(z, BUSY);
> > +	unlink_va(va, &fbl_root(z, BUSY));
> > +	fbl_unlock(z, BUSY);
> 
> I find the BUSY magic here very confusing, and would prefer to
> just spell the actual lock reference out.
>
No problem. I can make it open-coded. What is about an access to tree/list?

>> unlink_va(va, &fbl_root(z, BUSY));
I mean this one.

--
Uladzislau Rezki