From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Peter Xu" <peterx@redhat.com>, "Jan Kara" <jack@suse.cz>,
"Claudio Imbrenda" <imbrenda@linux.ibm.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH 4/4] mm/gup: remove get_user_pages_locked()
Date: Mon, 31 Jan 2022 12:01:54 -0800 [thread overview]
Message-ID: <d2f4a932-3cce-5b0d-fbf9-b9cf2291bb61@nvidia.com> (raw)
In-Reply-To: <20220131133612.GW8034@ziepe.ca>
On 1/31/22 05:36, Jason Gunthorpe wrote:
...
>> @@ -968,15 +966,15 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
>> if (flags & MPOL_F_NODE) {
>> if (flags & MPOL_F_ADDR) {
>> /*
>> - * Take a refcount on the mpol, lookup_node()
>> - * will drop the mmap_lock, so after calling
>> - * lookup_node() only "pol" remains valid, "vma"
>> - * is stale.
>> + * Take a refcount on the mpol, because we are about to
>> + * drop the mmap_lock, after which only "pol" remains
>> + * valid, "vma" is stale.
>> */
>> pol_refcount = pol;
>> vma = NULL;
>> mpol_get(pol);
>> err = lookup_node(mm, addr);
>> + mmap_read_unlock(mm);
>
> How about move the mmap_read_unlock up one line and then use
> get_user_pages_fast()
>
> I'm guessing in most cases here the PTE will be present so that should
> be a net win?
Neat, I'll do that.
thanks,
--
John Hubbard
NVIDIA
prev parent reply other threads:[~2022-01-31 20:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-31 5:17 [PATCH 0/4] mm/gup: some cleanups John Hubbard
2022-01-31 5:17 ` [PATCH 1/4] mm: Fix invalid page pointer returned with FOLL_PIN gups John Hubbard
2022-02-02 14:04 ` Christoph Hellwig
2022-01-31 5:17 ` [PATCH 2/4] mm/gup: clean up follow_pfn_pte() slightly John Hubbard
2022-01-31 13:36 ` Jason Gunthorpe
2022-01-31 5:17 ` [PATCH 3/4] mm/gup: remove unused pin_user_pages_locked() John Hubbard
2022-01-31 14:06 ` David Hildenbrand
2022-01-31 14:43 ` Jason Gunthorpe
2022-02-02 14:05 ` Christoph Hellwig
2022-01-31 5:17 ` [PATCH 4/4] mm/gup: remove get_user_pages_locked() John Hubbard
2022-01-31 12:05 ` Jan Kara
2022-01-31 20:01 ` John Hubbard
2022-01-31 13:36 ` Jason Gunthorpe
2022-01-31 20:01 ` John Hubbard [this message]
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