From: Richard Weinberger <richard.weinberger@gmail.com>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-embedded@vger.kernel.org" <linux-embedded@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Chris Brandt <Chris.Brandt@renesas.com>
Subject: Re: [PATCH v4 4/5] cramfs: add mmap support
Date: Tue, 3 Oct 2017 00:45:27 +0200 [thread overview]
Message-ID: <CAFLxGvzfQrvU-8w7F26mez6fCQD+iS_qRJpLSU+2DniEGouEfA@mail.gmail.com> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1710011805070.5407@knanqh.ubzr>
On Mon, Oct 2, 2017 at 12:29 AM, Nicolas Pitre <nicolas.pitre@linaro.org> wrote:
> On Sun, 1 Oct 2017, Christoph Hellwig wrote:
>
>> up_read(&mm->mmap_sem) in the fault path is a still a complete
>> no-go,
>>
>> NAK
>
> Care to elaborate?
>
> What about mm/filemap.c:__lock_page_or_retry() then?
As soon you up_read() in the page fault path other tasks will race
with you before
you're able to grab the write lock.
HTH
--
Thanks,
//richard
WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard.weinberger@gmail.com>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-embedded@vger.kernel.org" <linux-embedded@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Chris Brandt <Chris.Brandt@renesas.com>
Subject: Re: [PATCH v4 4/5] cramfs: add mmap support
Date: Tue, 3 Oct 2017 00:45:27 +0200 [thread overview]
Message-ID: <CAFLxGvzfQrvU-8w7F26mez6fCQD+iS_qRJpLSU+2DniEGouEfA@mail.gmail.com> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1710011805070.5407@knanqh.ubzr>
On Mon, Oct 2, 2017 at 12:29 AM, Nicolas Pitre <nicolas.pitre@linaro.org> wrote:
> On Sun, 1 Oct 2017, Christoph Hellwig wrote:
>
>> up_read(&mm->mmap_sem) in the fault path is a still a complete
>> no-go,
>>
>> NAK
>
> Care to elaborate?
>
> What about mm/filemap.c:__lock_page_or_retry() then?
As soon you up_read() in the page fault path other tasks will race
with you before
you're able to grab the write lock.
HTH
--
Thanks,
//richard
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next prev parent reply other threads:[~2017-10-02 22:45 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 23:32 [PATCH v4 0/5] cramfs refresh for embedded usage Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
2017-09-27 23:32 ` [PATCH v4 1/5] cramfs: direct memory access support Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
2017-10-01 8:29 ` Christoph Hellwig
2017-10-01 8:29 ` Christoph Hellwig
2017-10-01 22:27 ` Nicolas Pitre
2017-10-01 22:27 ` Nicolas Pitre
2017-10-03 14:59 ` Christoph Hellwig
2017-10-03 14:59 ` Christoph Hellwig
2017-10-03 15:06 ` Nicolas Pitre
2017-10-03 15:06 ` Nicolas Pitre
2017-10-03 14:43 ` Rob Herring
2017-10-03 14:43 ` Rob Herring
2017-10-03 14:58 ` Chris Brandt
2017-10-03 14:58 ` Chris Brandt
2017-09-27 23:32 ` [PATCH v4 2/5] cramfs: make cramfs_physmem usable as root fs Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
2017-09-27 23:32 ` [PATCH v4 3/5] cramfs: implement uncompressed and arbitrary data block positioning Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
2017-09-27 23:32 ` [PATCH v4 4/5] cramfs: add mmap support Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
2017-10-01 8:30 ` Christoph Hellwig
2017-10-01 8:30 ` Christoph Hellwig
2017-10-01 22:29 ` Nicolas Pitre
2017-10-01 22:29 ` Nicolas Pitre
2017-10-02 22:45 ` Richard Weinberger [this message]
2017-10-02 22:45 ` Richard Weinberger
2017-10-02 23:33 ` Nicolas Pitre
2017-10-02 23:33 ` Nicolas Pitre
2017-10-03 14:57 ` Christoph Hellwig
2017-10-03 14:57 ` Christoph Hellwig
2017-10-03 15:30 ` Nicolas Pitre
2017-10-03 15:30 ` Nicolas Pitre
2017-10-03 15:37 ` Christoph Hellwig
2017-10-03 15:37 ` Christoph Hellwig
2017-10-03 15:40 ` Nicolas Pitre
2017-10-03 15:40 ` Nicolas Pitre
2017-10-04 7:25 ` Christoph Hellwig
2017-10-04 7:25 ` Christoph Hellwig
2017-10-04 20:47 ` Nicolas Pitre
2017-10-04 20:47 ` Nicolas Pitre
2017-10-05 7:15 ` Christoph Hellwig
2017-10-05 7:15 ` Christoph Hellwig
2017-10-05 17:52 ` Nicolas Pitre
2017-10-05 17:52 ` Nicolas Pitre
2017-10-05 20:00 ` Chris Brandt
2017-10-05 20:00 ` Chris Brandt
2017-10-05 21:15 ` Nicolas Pitre
2017-10-05 21:15 ` Nicolas Pitre
2017-10-05 23:49 ` Chris Brandt
2017-10-05 23:49 ` Chris Brandt
2017-09-27 23:32 ` [PATCH v4 5/5] cramfs: rehabilitate it Nicolas Pitre
2017-09-27 23:32 ` Nicolas Pitre
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