linux-kernel - Re: [BUG] staging: android: ashmem: Deadlock during ashmem

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Message-ID: <CAG6tG3zcOdkA5QOBhaDzmMvcFSCwbfRAyKuRwXdn6ipOJhTVZQ@mail.gmail.com>
Date:	Tue, 23 Apr 2013 13:24:04 -0400
From:	Robert Love <rlove@...gle.com>
To:	Shankar Brahadeeswaran <shankoo77@...il.com>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Bjorn Bringert <bringert@...gle.com>,
	Al Viro <viro@...iv.linux.org.uk>, devel@...verdev.osuosl.org,
	Hugh Dickins <hughd@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Anjana V Kumar <anjanavk12@...il.com>
Subject: Re: [BUG] staging: android: ashmem: Deadlock during ashmem_shrink

On Tue, Apr 23, 2013 at 12:20 PM, Shankar Brahadeeswaran
<shankoo77@...il.com> wrote:

> I'm unable to think of a straight forward way to fix this. If you have
> any suggestions please provide the same.
> If we are unable to solve this too with minor mods, as suggested by
> Dan we have to re-look at the locking in this driver.

This doesn't look insurmountable. It isn't necessary AFAICT to hold
ashmem_mutex across shmem_file_setup.

Patch attached (untested).

           Robert

Download attachment "ashmem-lock-fix.patch" of type "application/octet-stream" (861 bytes)