From mboxrd@z Thu Jan  1 00:00:00 1970
From: dspjm1@gmail.com (Jimmy Pan)
Date: Fri, 4 Nov 2011 12:44:25 +0800
Subject: why does the kernel use mutex to protect the address_space
	structure
In-Reply-To: <CAFLer83bXuOnNgbFfScoQaysCi11Bb-BJuEAxcFwTy=UTV_ZsA@mail.gmail.com>
References: <CAFLer83bXuOnNgbFfScoQaysCi11Bb-BJuEAxcFwTy=UTV_ZsA@mail.gmail.com>
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To: kernelnewbies@lists.kernelnewbies.org
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On Tue, Nov 1, 2011 at 3:57 AM, Zheng Da <zhengda1936@gmail.com> wrote:
> Hello,
>
> I try to understand why the kernel uses mutex to protect the
> address_space structure. I checked the critical areas protected by
> i_mmap_mutex, and didn't see these areas use IO. I don't see why we
> can't use spin locks. Do I miss something? It seems most of critical
> areas provided by i_mmap_mutex aren't very large.
>
> Thanks,
> Da
>
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In my knowledge, when you use mutex, you can go to sleep, if you use spin lock,
the thread has to busy wait, spin lock causes cpu waste, while mutex
cannot be used
under interrupt context.

Regards,
Jimmy