From: Matthew Wilcox <willy@infradead.org>
To: Souptick Joarder <jrdr.linux@gmail.com>
Cc: mark.rutland@arm.com, sfr@canb.auug.org.au, kvm@vger.kernel.org,
pbonzini@redhat.com, linux-mm@kvack.org, peterz@infradead.org,
kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org,
acme@kernel.org, rppt@linux.ibm.com,
alexander.shishkin@linux.intel.com, mingo@redhat.com,
aneesh.kumar@linux.ibm.com, John Hubbard <jhubbard@nvidia.com>,
namhyung@kernel.org, akpm@linux-foundation.org,
msuchanek@suse.de, linuxppc-dev@lists.ozlabs.org
Subject: Re: [linux-next RFC] mm/gup.c: Convert to use get_user_pages_fast_only()
Date: Sat, 23 May 2020 10:25:19 -0700 [thread overview]
Message-ID: <20200523172519.GA17206@bombadil.infradead.org> (raw)
In-Reply-To: <1590252072-2793-1-git-send-email-jrdr.linux@gmail.com>
On Sat, May 23, 2020 at 10:11:12PM +0530, Souptick Joarder wrote:
> Renaming the API __get_user_pages_fast() to get_user_pages_
> fast_only() to align with pin_user_pages_fast_only().
Please don't split a function name across lines. That messes
up people who are grepping for the function name in the changelog.
> As part of this we will get rid of write parameter.
> Instead caller will pass FOLL_WRITE to get_user_pages_fast_only().
> This will not change any existing functionality of the API.
>
> All the callers are changed to pass FOLL_WRITE.
>
> Updated the documentation of the API.
Everything you have done here is an improvement, and I'd be happy to
see it go in (after fixing the bug I note below).
But in reading through it, I noticed almost every user ...
> - if (__get_user_pages_fast(hva, 1, 1, &page) == 1) {
> + if (get_user_pages_fast_only(hva, 1, FOLL_WRITE, &page) == 1) {
passes '1' as the second parameter. So do we want to add:
static inline bool get_user_page_fast_only(unsigned long addr,
unsigned int gup_flags, struct page **pagep)
{
return get_user_pages_fast_only(addr, 1, gup_flags, pagep) == 1;
}
> @@ -2797,10 +2803,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
> * FOLL_FAST_ONLY is required in order to match the API description of
> * this routine: no fall back to regular ("slow") GUP.
> */
> - unsigned int gup_flags = FOLL_GET | FOLL_FAST_ONLY;
> -
> - if (write)
> - gup_flags |= FOLL_WRITE;
> + gup_flags = FOLL_GET | FOLL_FAST_ONLY;
Er ... gup_flags |=, surely?
next prev parent reply other threads:[~2020-05-23 17:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-23 16:41 [linux-next RFC] mm/gup.c: Convert to use get_user_pages_fast_only() Souptick Joarder
2020-05-23 17:25 ` Matthew Wilcox [this message]
2020-05-23 19:35 ` Souptick Joarder
2020-05-23 22:18 ` John Hubbard
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=20200523172519.GA17206@bombadil.infradead.org \
--to=willy@infradead.org \
--cc=acme@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=aneesh.kumar@linux.ibm.com \
--cc=jhubbard@nvidia.com \
--cc=jrdr.linux@gmail.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=msuchanek@suse.de \
--cc=namhyung@kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rppt@linux.ibm.com \
--cc=sfr@canb.auug.org.au \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).