Re: [Bug #15805] reiserfs locking

[Frederic Weisbecker]

On Tue, Apr 20, 2010 at 05:19:25AM +0200, Rafael J. Wysocki wrote:
> This message has been generated automatically as a part of a summary report
> of recent regressions.
> 
> The following bug entry is on the current list of known regressions
> from 2.6.33.  Please verify if it still should be listed and let the tracking team
> know (either way).
> 
> 
> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=15805
> Subject		: reiserfs locking
> Submitter	: Alexander Beregalov <a.beregalov@xxxxxxxxx>
> Date		: 2010-04-15 21:02 (5 days old)
> Message-ID	: <t2ka4423d671004151402n7b2dc425mdc9c6bb9640d63fb@xxxxxxxxxxxxxx>
> References	: http://marc.info/?l=linux-kernel&m=127136535323933&w=2


That doesn't look like related to the bkl removal.

In fact what I wonder is how we missed that before.

vfs_readdir() take the directory inode mutex
    |
    ------- copy_to_user() takes the mm->mmap_sem

sys_unmap() takes mm->mmap_sem
    |
    ------- reiserfs_file_release() takes inode mutex


The lock inversion can not happen as sys_getdents() can't be called
after the directory is closed.

I'm not sure what to do. Adding more people in Cc.

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