linux-kernel - Re: [PATCH] hugetlb: remove unnecessary set_page_count in prep_compound_gigantic

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Message-ID: <YXiUHZOWnRsOM2HX@casper.infradead.org>
Date:   Wed, 27 Oct 2021 00:49:49 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pasha Tatashin <pasha.tatashin@...een.com>
Subject: Re: [PATCH] hugetlb: remove unnecessary set_page_count in
 prep_compound_gigantic_page

On Tue, Oct 26, 2021 at 03:06:35PM -0700, Mike Kravetz wrote:
> In commit 7118fc2906e29 ("hugetlb: address ref count racing in
> prep_compound_gigantic_page"), page_ref_freeze is used to atomically
> zero the ref count of tail pages iff they are 1.  The unconditional
> call to set_page_count(0) was left in the code.  This call is after
> page_ref_freeze so it is really a noop.
> 
> Remove redundant and unnecessary set_page_count call.
> 
> Fixes: 7118fc2906e29 ("hugetlb: address ref count racing in prep_compound_gigantic_page")
> Suggested-by: Pasha Tatashin <pasha.tatashin@...een.com>
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>