lkml.org 
[lkml]   [2010]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 0/2] Fix up the NFS mmap code


On Sat, 9 Jan 2010, Al Viro wrote:
>
> Well, sure - it steps on i_mutex-before-mmmap_sem first from ls somewhere and
> records the ordering for posterity. Then NFS steps into mmap() (on a
> different inode) and gets conflicting ordering.

Look closer: the inodes for directories and for non-directories have
i_mutex in different lockdep classes.

So that "on a different inode" thing should have made it a non-issue,
since there is no actual chain back. There is "mmap_sem ->
i_mutex_regular_file" (for mmap) and there is "i_mutex_directory ->
mmap_sem" (for filldir), but that isn't an ABBA.

The problem _seems_ to be (if I read Andi's chain correctly) that a
directory hasn't gone through the i_mutex_dir_key change, so filldir ends
up being counted against the default i_mutex_key.


Linus


\
 
 \ /
  Last update: 2010-01-09 03:25    [W:0.057 / U:0.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site