From: Lorenzo Stoakes <lstoakes@gmail.com>
To: linux-mm@kvack.org
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
"Michal Hocko" <mhocko@kernel.org>, "Jan Kara" <jack@suse.cz>,
"Hugh Dickins" <hughd@google.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Rik van Riel" <riel@redhat.com>,
"Mel Gorman" <mgorman@techsingularity.net>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: remove unnecessary __get_user_pages_unlocked() calls
Date: Wed, 26 Oct 2016 08:59:52 +0100 [thread overview]
Message-ID: <20161026075952.GA30977@lucifer> (raw)
In-Reply-To: <20161025233609.5601-1-lstoakes@gmail.com>
On Wed, Oct 26, 2016 at 12:36:09AM +0100, Lorenzo Stoakes wrote:
> In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked() with
> get_user_pages_unlocked() since we can now pass gup_flags.
>
> In async_pf_execute() we need to pass different tsk, mm arguments so
> get_user_pages_remote() is the sane replacement here (having added manual
> acquisition and release of mmap_sem.)
>
> Since we pass a NULL pages parameter the subsequent call to
> __get_user_pages_locked() will have previously bailed any attempt at
> VM_FAULT_RETRY, so we do not change this behaviour by using
> get_user_pages_remote() which does not invoke VM_FAULT_RETRY logic at all.
>
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Note that the use of get_user_pages_remote() in async_pf_execute() reintroduces
the use of the FOLL_TOUCH flag - I don't think this is a problem as this flag
was dropped by 1e987790 ("mm/gup: Introduce get_user_pages_remote()") which
states 'Without protection keys, this patch should not change any behavior', so
I don't think this was intentional.
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next prev parent reply other threads:[~2016-10-26 7:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-25 23:36 [PATCH] mm: remove unnecessary __get_user_pages_unlocked() calls Lorenzo Stoakes
2016-10-25 23:46 ` Lorenzo Stoakes
2016-10-26 9:15 ` Michal Hocko
2016-10-26 9:39 ` Lorenzo Stoakes
2016-10-26 9:54 ` Michal Hocko
2016-10-26 7:59 ` Lorenzo Stoakes [this message]
2016-10-26 9:07 ` Michal Hocko
2016-10-26 9:12 ` Michal Hocko
2016-10-26 9:25 ` [PATCH v2] " Lorenzo Stoakes
2016-10-27 0:12 ` Andrew Morton
2016-10-27 7:06 ` Lorenzo Stoakes
2016-10-27 9:27 ` Paolo Bonzini
2016-10-27 9:32 ` Lorenzo Stoakes
2016-10-27 9:35 ` Paolo Bonzini
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