From: Jason Gunthorpe <jgg@nvidia.com>
To: peterx@redhat.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Muchun Song <muchun.song@linux.dev>,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
x86@kernel.org, sparclinux@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH RFC 03/13] mm/gup: Check p4d presence before going on
Date: Thu, 7 Mar 2024 16:08:26 -0400 [thread overview]
Message-ID: <20240307200826.GE9179@nvidia.com> (raw)
In-Reply-To: <20240306104147.193052-4-peterx@redhat.com>
On Wed, Mar 06, 2024 at 06:41:37PM +0800, peterx@redhat.com wrote:
> From: Peter Xu <peterx@redhat.com>
>
> Currently there should have no p4d swap entries so it may not matter much,
> however this may help us to rule out swap entries in pXd_huge() API, which
> will include p4d_huge(). The p4d_present() checks make it 100% clear that
> we won't rely on p4d_huge() for swap entries.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> mm/gup.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> p4dp = p4d_offset(pgdp, address);
> p4d = READ_ONCE(*p4dp);
> - if (p4d_none(p4d))
> + if (p4d_none(p4d) || !p4d_present(p4d))
> return no_page_table(vma, flags);
Like the other place I think this makes more sense as
if (!p4_present(p4d))
return no_page_table(vma, flags);
Since none can never be present.
IOW if the following code doesn't decode swap entries then it should
be guarded with a chceck on present not none..
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: peterx@redhat.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Muchun Song <muchun.song@linux.dev>,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
x86@kernel.org, sparclinux@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH RFC 03/13] mm/gup: Check p4d presence before going on
Date: Thu, 7 Mar 2024 16:08:26 -0400 [thread overview]
Message-ID: <20240307200826.GE9179@nvidia.com> (raw)
In-Reply-To: <20240306104147.193052-4-peterx@redhat.com>
On Wed, Mar 06, 2024 at 06:41:37PM +0800, peterx@redhat.com wrote:
> From: Peter Xu <peterx@redhat.com>
>
> Currently there should have no p4d swap entries so it may not matter much,
> however this may help us to rule out swap entries in pXd_huge() API, which
> will include p4d_huge(). The p4d_present() checks make it 100% clear that
> we won't rely on p4d_huge() for swap entries.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> mm/gup.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> p4dp = p4d_offset(pgdp, address);
> p4d = READ_ONCE(*p4dp);
> - if (p4d_none(p4d))
> + if (p4d_none(p4d) || !p4d_present(p4d))
> return no_page_table(vma, flags);
Like the other place I think this makes more sense as
if (!p4_present(p4d))
return no_page_table(vma, flags);
Since none can never be present.
IOW if the following code doesn't decode swap entries then it should
be guarded with a chceck on present not none..
Jason
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: peterx@redhat.com
Cc: linux-arm-kernel@lists.infradead.org, x86@kernel.org,
Muchun Song <muchun.song@linux.dev>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
linux-mm@kvack.org, sparclinux@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH RFC 03/13] mm/gup: Check p4d presence before going on
Date: Thu, 7 Mar 2024 16:08:26 -0400 [thread overview]
Message-ID: <20240307200826.GE9179@nvidia.com> (raw)
In-Reply-To: <20240306104147.193052-4-peterx@redhat.com>
On Wed, Mar 06, 2024 at 06:41:37PM +0800, peterx@redhat.com wrote:
> From: Peter Xu <peterx@redhat.com>
>
> Currently there should have no p4d swap entries so it may not matter much,
> however this may help us to rule out swap entries in pXd_huge() API, which
> will include p4d_huge(). The p4d_present() checks make it 100% clear that
> we won't rely on p4d_huge() for swap entries.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> mm/gup.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> p4dp = p4d_offset(pgdp, address);
> p4d = READ_ONCE(*p4dp);
> - if (p4d_none(p4d))
> + if (p4d_none(p4d) || !p4d_present(p4d))
> return no_page_table(vma, flags);
Like the other place I think this makes more sense as
if (!p4_present(p4d))
return no_page_table(vma, flags);
Since none can never be present.
IOW if the following code doesn't decode swap entries then it should
be guarded with a chceck on present not none..
Jason
next prev parent reply other threads:[~2024-03-07 20:08 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-06 10:41 [PATCH RFC 00/13] mm/treewide: Remove pXd_huge() API peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 01/13] mm/hmm: Process pud swap entry without pud_huge() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-07 18:12 ` Jason Gunthorpe
2024-03-07 18:12 ` Jason Gunthorpe
2024-03-07 18:12 ` Jason Gunthorpe
2024-03-08 6:50 ` Peter Xu
2024-03-08 6:50 ` Peter Xu
2024-03-08 6:50 ` Peter Xu
2024-03-06 10:41 ` [PATCH RFC 02/13] mm/gup: Cache p4d in follow_p4d_mask() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 03/13] mm/gup: Check p4d presence before going on peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-07 20:08 ` Jason Gunthorpe [this message]
2024-03-07 20:08 ` Jason Gunthorpe
2024-03-07 20:08 ` Jason Gunthorpe
2024-03-06 10:41 ` [PATCH RFC 04/13] mm/x86: Change pXd_huge() behavior to exclude swap entries peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-07 20:16 ` Jason Gunthorpe
2024-03-07 20:16 ` Jason Gunthorpe
2024-03-07 20:16 ` Jason Gunthorpe
2024-03-06 10:41 ` [PATCH RFC 05/13] mm/sparc: " peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 06/13] mm/arm: Use macros to define pmd/pud helpers peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 07/13] mm/arm: Redefine pmd_huge() with pmd_leaf() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 08/13] mm/arm64: Merge pXd_huge() and pXd_leaf() definitions peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 09/13] mm/powerpc: Redefine pXd_huge() with pXd_leaf() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 12:56 ` Michael Ellerman
2024-03-06 12:56 ` Michael Ellerman
2024-03-06 12:56 ` Michael Ellerman
2024-03-07 3:05 ` Peter Xu
2024-03-07 3:05 ` Peter Xu
2024-03-07 3:05 ` Peter Xu
2024-03-06 10:41 ` [PATCH RFC 10/13] mm/gup: Merge pXd huge mapping checks peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-07 20:19 ` Jason Gunthorpe
2024-03-07 20:19 ` Jason Gunthorpe
2024-03-07 20:19 ` Jason Gunthorpe
2024-03-06 10:41 ` [PATCH RFC 11/13] mm/treewide: Replace pXd_huge() with pXd_leaf() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 12/13] mm/treewide: Remove pXd_huge() peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` [PATCH RFC 13/13] mm: Document pXd_leaf() API peterx
2024-03-06 10:41 ` peterx
2024-03-06 10:41 ` peterx
2024-03-08 15:20 ` Jason Gunthorpe
2024-03-08 15:20 ` Jason Gunthorpe
2024-03-08 15:20 ` Jason Gunthorpe
2024-03-11 9:58 ` [PATCH RFC 00/13] mm/treewide: Remove pXd_huge() API Christophe Leroy
2024-03-11 9:58 ` Christophe Leroy
2024-03-11 9:58 ` Christophe Leroy
2024-03-12 20:01 ` Peter Xu
2024-03-12 20:01 ` Peter Xu
2024-03-12 20:01 ` Peter Xu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240307200826.GE9179@nvidia.com \
--to=jgg@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=christophe.leroy@csgroup.eu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=muchun.song@linux.dev \
--cc=peterx@redhat.com \
--cc=rppt@kernel.org \
--cc=sparclinux@vger.kernel.org \
--cc=willy@infradead.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.