linux-kernel - Re: [PATCH] mm/z3fold.c: Allow __GFP_HIGHMEM in z3fold

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Date:   Sat, 13 Jul 2019 09:05:27 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Henry Burns <henryburns@...gle.com>
Cc:     Vitaly Wool <vitalywool@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vitaly Vul <vitaly.vul@...y.com>,
        Jonathan Adams <jwadams@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Snild Dolkow <snild@...y.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/z3fold.c: Allow __GFP_HIGHMEM in z3fold_alloc

On Fri, Jul 12, 2019 at 3:22 PM Henry Burns <henryburns@...gle.com> wrote:
>
> One of the gfp flags used to show that a page is movable is
> __GFP_HIGHMEM.  Currently z3fold_alloc() fails when __GFP_HIGHMEM is
> passed.  Now that z3fold pages are movable, we allow __GFP_HIGHMEM. We
> strip the movability related flags from the call to kmem_cache_alloc()
> for our slots since it is a kernel allocation.
>
> Signed-off-by: Henry Burns <henryburns@...gle.com>

Reviewed-by: Shakeel Butt <shakeelb@...gle.com>

> ---
>  mm/z3fold.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index e78f95284d7c..cb567ddf051c 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -193,7 +193,8 @@ static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
>                                                         gfp_t gfp)
>  {
>         struct z3fold_buddy_slots *slots = kmem_cache_alloc(pool->c_handle,
> -                                                           gfp);
> +                                                           (gfp & ~(__GFP_HIGHMEM
> +                                                                  | __GFP_MOVABLE)));
>
>         if (slots) {
>                 memset(slots->slot, 0, sizeof(slots->slot));
> @@ -844,7 +845,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
>         enum buddy bud;
>         bool can_sleep = gfpflags_allow_blocking(gfp);
>
> -       if (!size || (gfp & __GFP_HIGHMEM))
> +       if (!size)
>                 return -EINVAL;
>
>         if (size > PAGE_SIZE)
> --
> 2.22.0.510.g264f2c817a-goog
>