linux-kernel - Re: [PATCH v2 1/4] mm/vmalloc: invoke classify_va_fit_type() in adjust_va_to_fit

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Message-ID: <CA+KHdyVMh-yWJaWc+9o0DhP8TG9Nvua6EywRAwEJjqfTgDXAJQ@mail.gmail.com>
Date:   Tue, 7 Jun 2022 14:53:52 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2 1/4] mm/vmalloc: invoke classify_va_fit_type() in adjust_va_to_fit_type()

>
> In function adjust_va_to_fit_type(), it checks all values of passed
> in fit type, including NOTHING_FIT in the else branch. However, the
> check of NOTHING_FIT has been done inside adjust_va_to_fit_type() and
> before it's called in all call sites.
>
> In fact, both of these two functions are coupled tightly, since
> classify_va_fit_type() is doing the preparation work for
> adjust_va_to_fit_type(). So putting invocation of classify_va_fit_type()
> inside adjust_va_to_fit_type() can simplify code logic and the redundant
> check of NOTHING_FIT issue will go away.
>
> Suggested-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  mm/vmalloc.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 07db42455dd4..f9d45aa90b7c 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1335,10 +1335,10 @@ classify_va_fit_type(struct vmap_area *va,
>
>  static __always_inline int
>  adjust_va_to_fit_type(struct vmap_area *va,
> -       unsigned long nva_start_addr, unsigned long size,
> -       enum fit_type type)
> +       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);
>
>         if (type == FL_FIT_TYPE) {
>                 /*
> @@ -1444,7 +1444,6 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
>         bool adjust_search_size = true;
>         unsigned long nva_start_addr;
>         struct vmap_area *va;
> -       enum fit_type type;
>         int ret;
>
>         /*
> @@ -1472,14 +1471,9 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
>         if (nva_start_addr + size > vend)
>                 return vend;
>
> -       /* Classify what we have found. */
> -       type = classify_va_fit_type(va, nva_start_addr, size);
> -       if (WARN_ON_ONCE(type == NOTHING_FIT))
> -               return vend;
> -
>         /* Update the free vmap_area. */
> -       ret = adjust_va_to_fit_type(va, nva_start_addr, size, type);
> -       if (ret)
> +       ret = adjust_va_to_fit_type(va, nva_start_addr, size);
> +       if (WARN_ON_ONCE(ret))
>                 return vend;
>
>  #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
> @@ -3735,7 +3729,6 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>         int area, area2, last_area, term_area;
>         unsigned long base, start, size, end, last_end, orig_start, orig_end;
>         bool purged = false;
> -       enum fit_type type;
>
>         /* verify parameters and allocate data structures */
>         BUG_ON(offset_in_page(align) || !is_power_of_2(align));
> @@ -3846,15 +3839,11 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>                         /* It is a BUG(), but trigger recovery instead. */
>                         goto recovery;
>
> -               type = classify_va_fit_type(va, start, size);
> -               if (WARN_ON_ONCE(type == NOTHING_FIT))
> +               ret = adjust_va_to_fit_type(va, start, size);
> +               if (WARN_ON_ONCE(unlikely(ret)))
>                         /* It is a BUG(), but trigger recovery instead. */
>                         goto recovery;
>
> -               ret = adjust_va_to_fit_type(va, start, size, type);
> -               if (unlikely(ret))
> -                       goto recovery;
> -
>                 /* Allocated area. */
>                 va = vas[area];
>                 va->va_start = start;
> --
> 2.34.1
>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>

-- 
Uladzislau Rezki