linux-mips.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Paul Burton <paul.burton@mips.com>
To: Davidlohr Bueso <dave@stgolabs.net>
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 19:00:09 +0000	[thread overview]
Message-ID: <20190207190007.jz4rz6e6qxwazxm7@pburton-laptop> (raw)
In-Reply-To: <20190207053740.26915-3-dave@stgolabs.net>

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.

Thanks,
    Paul

  reply	other threads:[~2019-02-07 19:00 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 [this message]
2019-02-07 19:25     ` Davidlohr Bueso

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=20190207190007.jz4rz6e6qxwazxm7@pburton-laptop \
    --to=paul.burton@mips.com \
    --cc=akpm@linux-foundation.org \
    --cc=dave@stgolabs.net \
    --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=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).