linux-kernel - Re: [PATCH 2/9] mm: vmalloc: Rename adjust_va_to_fit

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Date:   Wed, 24 May 2023 13:51:28 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        "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>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        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 2/9] mm: vmalloc: Rename adjust_va_to_fit_type() function

On Tue, May 23, 2023 at 01:24:09PM -0400, Liam R. Howlett wrote:
> * Uladzislau Rezki (Sony) <urezki@...il.com> [230522 07:09]:
> > This patch renames the adjust_va_to_fit_type() function
> > to a shorter variant and more expressive. A new name is
> > va_clip().
> > 
> > There is no a functional change as a result of this patch.
> > 
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> > ---
> >  mm/vmalloc.c | 13 ++++++-------
> >  1 file changed, 6 insertions(+), 7 deletions(-)
> > 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 409285b68a67..5f900efec6a9 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -1383,9 +1383,9 @@ classify_va_fit_type(struct vmap_area *va,
> >  }
> >  
> >  static __always_inline int
> > -adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
> > -		      struct vmap_area *va, unsigned long nva_start_addr,
> > -		      unsigned long size)
> > +va_clip(struct rb_root *root, struct list_head *head,
> > +	struct vmap_area *va, unsigned long nva_start_addr,
> > +	unsigned long size)
> >  {
> >  	struct vmap_area *lva = NULL;
> >  	enum fit_type type = classify_va_fit_type(va, nva_start_addr, size);
> > @@ -1501,7 +1501,7 @@ va_alloc(struct vmap_area *va,
> >  		return vend;
> >  
> >  	/* Update the free vmap_area. */
> > -	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
> > +	ret = va_clip(root, head, va, nva_start_addr, size);
> >  	if (WARN_ON_ONCE(ret))
> 
> ret is only used in this WARN_ON_ONCE() check (from patch 1), since you
> have shortened adjust_va_to_fit_type(), you can probably drop the ret
> variable all together here?
> 
I can move the WARN_ON_ONCE() check into the va_clip(). So it makes sense.

As for a return value, we should check it, at least here:

		ret = va_clip(&free_vmap_area_root,
			&free_vmap_area_list, va, start, size);
		if (WARN_ON_ONCE(unlikely(ret)))
			/* It is a BUG(), but trigger recovery instead. */
			goto recovery;



i t can fail, though it rather goes toward almost zero%.

Thank you for looking at it, Liam!

--
Uladzuslau Rezki