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From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Jerome Marchand <jmarchan@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>,
	John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
	Yang Shi <shy828301@gmail.com>
Subject: Re: [PATCH v1] mm/gup: adjust stale comment for RCU GUP-fast
Date: Thu, 1 Sep 2022 13:12:35 -0300	[thread overview]
Message-ID: <YxDZ86XW3hPcJtPX@nvidia.com> (raw)
In-Reply-To: <20220901072119.37588-1-david@redhat.com>

On Thu, Sep 01, 2022 at 09:21:19AM +0200, David Hildenbrand wrote:
> commit 4b471e8898c3 ("mm, thp: remove infrastructure for handling splitting
> PMDs") didn't remove all details about the THP split requirements for
> RCU GUP-fast.
> 
> IPI broeadcasts on THP split are no longer required.
> 
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Sasha Levin <sasha.levin@oracle.com>
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Jerome Marchand <jmarchan@redhat.com>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Jason Gunthorpe <jgg@nvidia.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  mm/gup.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)

The comment a bit above seems to need touching to:

 * protected from page table pages being freed from under it, and should
 * block any THP splits.

What is the current situation for THP splits anyhow? Is there are
comment in the fast pmd code explaining it?

But this seems OK too

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

  parent reply	other threads:[~2022-09-01 16:12 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-01  7:21 [PATCH v1] mm/gup: adjust stale comment for RCU GUP-fast David Hildenbrand
2022-09-01 14:37 ` Kirill A . Shutemov
2022-09-01 16:12 ` Jason Gunthorpe [this message]
2022-09-01 16:30   ` David Hildenbrand
2022-09-01 16:28 ` Peter Xu
2022-09-01 16:34   ` David Hildenbrand
2022-09-01 16:40     ` Peter Xu
2022-09-01 16:46       ` David Hildenbrand
2022-09-01 17:41         ` Peter Xu
2022-09-01 17:44           ` David Hildenbrand
2022-09-01 17:50         ` Yang Shi
2022-09-01 18:07           ` Peter Xu
2022-09-01 18:35             ` Yang Shi
2022-09-02  6:32               ` David Hildenbrand
2022-09-02 13:53                 ` Peter Xu
2022-09-02 15:37                 ` Yang Shi
2022-09-04 16:52                 ` Aneesh Kumar K V
2022-09-05  8:38                   ` David Hildenbrand
2022-09-05  8:41                     ` Aneesh Kumar K V
2022-09-04 16:49     ` Aneesh Kumar K V
2022-09-05  8:02       ` David Hildenbrand

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