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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Khalid Aziz <khalid.aziz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Anatoly Pugachev <matorola@gmail.com>,
	sparclinux@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 09/16] sparc64: use the generic get_user_pages_fast code
Date: Wed, 17 Jul 2019 17:17:16 -0700	[thread overview]
Message-ID: <CAHk-=wgjmt2i37nn9v+nGC0m8-DdLBMEs=NC=TV-u+9XAzA61g@mail.gmail.com> (raw)
In-Reply-To: <20190717233031.GB30369@altlinux.org>

On Wed, Jul 17, 2019 at 4:30 PM Dmitry V. Levin <ldv@altlinux.org> wrote:
>
> Sure, here it is:

Hmm. I'm not seeing anything obviously wrong in the generic gup conversion.

From the oops, I assume that the problem is that get_user_pages_fast()
returned an invalid page, causing the bad access later in
get_futex_key(). But that's odd too, considering that
get_user_pages_fast() had already accessed the page (both for looking
up the head, and for then doing things like SetPageReferenced(page)).

The only half-way subtle thing is the pte_access_permitted() movement,
but it looks like it matches what gup_pte_range() did in the original
sparc64 code. And the address masking is done the same way too, as far
as I can tell.

So clearly there's something wrong there, but I'm not seeing it. Maybe
I'm incorrectly looking at that pte case, and the problem happened
earlier.

Anyway, I suspect some sparc64 person needs to delve into it.

I know this got reviewed by sparc64 people (the final commit message
only has a single Reviewed-by, but I see an Ack by Davem in my maill
that seems to have gotten lost by the time the patch made it in), but
maybe actually nobody ever _tested_ it until it hit my tree?

                   Linus

  reply	other threads:[~2019-07-18  0:17 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-25 14:36 switch the remaining architectures to use generic GUP v4 Christoph Hellwig
2019-06-25 14:37 ` [PATCH 01/16] mm: use untagged_addr() for get_user_pages_fast addresses Christoph Hellwig
2019-06-25 14:37 ` [PATCH 02/16] mm: simplify gup_fast_permitted Christoph Hellwig
2019-06-25 14:37 ` [PATCH 03/16] mm: lift the x86_32 PAE version of gup_get_pte to common code Christoph Hellwig
2019-06-25 14:37 ` [PATCH 04/16] MIPS: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-29 14:37   ` Guenter Roeck
2019-06-25 14:37 ` [PATCH 05/16] sh: add the missing pud_page definition Christoph Hellwig
2019-06-25 14:37 ` [PATCH 06/16] sh: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-29 15:15   ` Guenter Roeck
2019-06-25 14:37 ` [PATCH 07/16] sparc64: add the missing pgd_page definition Christoph Hellwig
2019-06-25 14:37 ` [PATCH 08/16] sparc64: define untagged_addr() Christoph Hellwig
2019-06-25 14:37 ` [PATCH 09/16] sparc64: use the generic get_user_pages_fast code Christoph Hellwig
2019-07-17 21:59   ` Dmitry V. Levin
2019-07-17 22:04     ` Linus Torvalds
2019-07-17 23:30       ` Dmitry V. Levin
2019-07-18  0:17         ` Linus Torvalds [this message]
2019-07-18  1:21           ` David Miller
2019-07-18 21:43           ` David Miller
2019-07-18 21:14     ` David Miller
2019-07-19  6:00       ` Christoph Hellwig
2019-07-24 19:32       ` Anatoly Pugachev
2019-07-24 20:13         ` David Miller
2019-07-25 18:33           ` Anatoly Pugachev
2019-07-25 22:52             ` David Miller
2019-07-28  2:09             ` David Miller
2019-07-28 20:00               ` Anatoly Pugachev
2019-07-26 17:58     ` Khalid Aziz
2019-08-09 19:59     ` Anatoly Pugachev
2019-08-10  7:17       ` Christoph Hellwig
2019-08-10 19:36         ` Mikael Pettersson
2019-08-11 20:30           ` Anatoly Pugachev
2019-06-25 14:37 ` [PATCH 10/16] mm: rename CONFIG_HAVE_GENERIC_GUP to CONFIG_HAVE_FAST_GUP Christoph Hellwig
2019-06-25 14:37 ` [PATCH 11/16] mm: reorder code blocks in gup.c Christoph Hellwig
2019-06-25 14:37 ` [PATCH 12/16] mm: consolidate the get_user_pages* implementations Christoph Hellwig
2019-06-25 14:37 ` [PATCH 13/16] mm: validate get_user_pages_fast flags Christoph Hellwig
2019-06-25 14:37 ` [PATCH 14/16] mm: move the powerpc hugepd code to mm/gup.c Christoph Hellwig
2019-06-25 19:37   ` Andrew Morton
2019-06-26  5:49     ` Christoph Hellwig
2019-06-25 14:37 ` [PATCH 15/16] mm: switch gup_hugepte to use try_get_compound_head Christoph Hellwig
2019-06-25 14:37 ` [PATCH 16/16] mm: mark the page referenced in gup_hugepte Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2019-06-11 14:40 switch the remaining architectures to use generic GUP v3 Christoph Hellwig
2019-06-11 14:40 ` [PATCH 09/16] sparc64: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-11 19:35   ` Khalid Aziz

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