From: Davidlohr Bueso <dave@stgolabs.net>
To: Paul Burton <paul.burton@mips.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ralf Baechle <ralf@linux-mips.org>,
James Hogan <jhogan@kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast()
Date: Thu, 7 Feb 2019 11:25:55 -0800 [thread overview]
Message-ID: <20190207192555.n3qtle4yqmfb2tpo@linux-r8p5> (raw)
In-Reply-To: <20190207190007.jz4rz6e6qxwazxm7@pburton-laptop>
On Thu, 07 Feb 2019, Paul Burton wrote:
>Hi Davidlohr,
>
>On Wed, Feb 06, 2019 at 09:37:40PM -0800, Davidlohr Bueso wrote:
>> It is well known that because the mm can internally
>> call the regular gup_unlocked if the lockless approach
>> fails and take the sem there, the caller must not hold
>> the mmap_sem already.
>>
>> Fixes: e523f289fe4d (MIPS: c-r4k: Fix sigtramp SMP call to use kmap)
>> Cc: Ralf Baechle <ralf@linux-mips.org>
>> Cc: Paul Burton <paul.burton@mips.com>
>> Cc: James Hogan <jhogan@kernel.org>
>> Cc: linux-mips@vger.kernel.org
>> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
>
>Thanks - this looks good, but:
>
> 1) The problem it fixes was introduced in v4.8.
>
> 2) Commit adcc81f148d7 ("MIPS: math-emu: Write-protect delay slot
> emulation pages") actually left flush_cache_sigtramp unused, and has
> been backported to stable kernels also as far as v4.8.
>
>Therefore this will just fix code that never gets called, and I'll go
>delete the whole thing instead.
Even better.
Thanks,
Davidlohr
prev parent reply other threads:[~2019-02-07 19:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190207053740.26915-1-dave@stgolabs.net>
2019-02-07 5:37 ` [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast() Davidlohr Bueso
2019-02-07 19:00 ` Paul Burton
2019-02-07 19:25 ` Davidlohr Bueso [this message]
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=20190207192555.n3qtle4yqmfb2tpo@linux-r8p5 \
--to=dave@stgolabs.net \
--cc=akpm@linux-foundation.org \
--cc=dbueso@suse.de \
--cc=jhogan@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=paul.burton@mips.com \
--cc=ralf@linux-mips.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 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).