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From: Michel Lespinasse <walken@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	 LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	 Laurent Dufour <ldufour@linux.ibm.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	 Liam Howlett <Liam.Howlett@oracle.com>,
	Jerome Glisse <jglisse@redhat.com>,
	 Davidlohr Bueso <dave@stgolabs.net>,
	David Rientjes <rientjes@google.com>,
	Hugh Dickins <hughd@google.com>,  Ying Han <yinghan@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	 Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH v4 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER
Date: Mon, 20 Apr 2020 17:57:16 -0700	[thread overview]
Message-ID: <CANN689EDVibi-EO9+S01qLW7gSpzj3i7g9g=GiH5vGGKgFz2Qg@mail.gmail.com> (raw)
In-Reply-To: <20200420192806.GE5820@bombadil.infradead.org>

On Mon, Apr 20, 2020 at 12:28 PM Matthew Wilcox <willy@infradead.org> 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.


  reply	other threads:[~2020-04-21  0:57 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  0:43 [PATCH v4 00/10] Add a new mmap locking API wrapping mmap_sem calls Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 01/10] mmap locking API: initial implementation as rwsem wrappers Michel Lespinasse
2020-04-20 19:48   ` Davidlohr Bueso
2020-04-21  0:48     ` Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 02/10] MMU notifier: use the new mmap locking API Michel Lespinasse
2020-04-20 19:51   ` Davidlohr Bueso
2020-04-15  0:43 ` [PATCH v4 03/10] DMA reservations: " Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 04/10] mmap locking API: use coccinelle to convert mmap_sem rwsem call sites Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 05/10] mmap locking API: convert mmap_sem call sites missed by coccinelle Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 06/10] mmap locking API: convert nested write lock sites Michel Lespinasse
2020-04-20 18:19   ` Daniel Jordan
2020-04-20 19:33   ` Matthew Wilcox
2020-04-21  0:51     ` Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 07/10] mmap locking API: add mmap_read_trylock_non_owner() Michel Lespinasse
2020-04-20 18:22   ` Daniel Jordan
2020-04-20 19:23     ` Matthew Wilcox
2020-04-21  0:55       ` Michel Lespinasse
2020-04-15  0:43 ` [PATCH v4 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER Michel Lespinasse
2020-04-20 18:23   ` Daniel Jordan
2020-04-20 19:28   ` Matthew Wilcox
2020-04-21  0:57     ` Michel Lespinasse [this message]
2020-04-15  0:43 ` [PATCH v4 09/10] mmap locking API: use lockdep_assert_held Michel Lespinasse
2020-04-21  2:35   ` Matthew Wilcox
2020-04-15  0:43 ` [PATCH v4 10/10] mmap locking API: rename mmap_sem to mmap_lock Michel Lespinasse
2020-04-20 18:28   ` Daniel Jordan
2020-04-21  5:33   ` kbuild test robot
2020-04-21 22:19     ` Michel Lespinasse

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