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From:   Pasha Tatashin <pasha.tatashin@soleen.com>
Date:   Wed, 27 Oct 2021 14:22:58 -0400
Message-ID: <CA+CK2bA3aXXb4j9GwwWakZE+M9Fipet7eZioUsg_Ljx0UuTooA@mail.gmail.com>
Subject: Re: [RFC 1/8] mm: add overflow and underflow checks for page->_refcount
To:     Matthew Wilcox <willy@infradead.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
        linux-m68k@lists.linux-m68k.org,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        william.kucharski@oracle.com,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        schmitzmic@gmail.com, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Roman Gushchin <guro@fb.com>,
        Muchun Song <songmuchun@bytedance.com>, weixugc@google.com,
        Greg Thelen <gthelen@google.com>
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On Tue, Oct 26, 2021 at 11:05 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Tue, Oct 26, 2021 at 09:21:29PM -0400, Pasha Tatashin wrote:
> > I think we can do that by using:
> > atomic_fetch_*() and check for overflow/underflow after operation. I
> > will send the updated series soon.
>
> Please include performance measurements.  You're adding code to some hot
> paths.

I will do boot performance tests to ensure we do not regress
initializing "struct pages" on larger machines. Do you have a
suggestion for another perf test?

Thanks,
Pasha