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Mon, 20 Apr 2020 17:57:30 -0700 (PDT) MIME-Version: 1.0 References: <20200415004353.130248-1-walken@google.com> <20200415004353.130248-9-walken@google.com> <20200420192806.GE5820@bombadil.infradead.org> In-Reply-To: <20200420192806.GE5820@bombadil.infradead.org> From: Michel Lespinasse Date: Mon, 20 Apr 2020 17:57:16 -0700 Message-ID: Subject: Re: [PATCH v4 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER To: Matthew Wilcox Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , Laurent Dufour , Vlastimil Babka , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Apr 20, 2020 at 12:28 PM Matthew Wilcox wrote: > > On Tue, Apr 14, 2020 at 05:43:51PM -0700, Michel Lespinasse wrote: > > @@ -90,7 +90,7 @@ static struct mm_struct tboot_mm = { > ^^^^^^^^ > > .pgd = swapper_pg_dir, > > .mm_users = ATOMIC_INIT(2), > > .mm_count = ATOMIC_INIT(1), > > - .mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem), > > + .mmap_sem = MMAP_LOCK_INITIALIZER(init_mm.mmap_sem), > ^^^^^^^ > > Shome mishtake, shirley? > > I don't see that this particular patch buys us much. The name 'mmap_sem' > is still used, and I appreciate we abstract away the type of the lock, > but wouldn't this be better? > > - .mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem), > + MMAP_LOCK_INITIALIZER(tboot_mm), Hmmm, that's significantly different from other initializers we have, which may be a downside ? But other than that, it does seem completely workable to me. Do you have a strong preference ? -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies.