Re: fs/dcache.c - BUG: soft lockup - CPU#5 stuck for 22s! [systemd-udevd:1667]

[Al Viro <viro@ZenIV.linux.org.uk>]

On Fri, May 30, 2014 at 11:12:38AM +0300, Mika Westerberg wrote:

> Tested your latest #for-linus from here:
> 
> https://git.kernel.org/cgit/linux/kernel/git/viro/vfs.git/log/?h=for-linus
> 
> and the livelock is gone,
> 
> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> 
> Thanks again!

OK...  I've just pushed another branch (#for-linus-2) with lock_parent()
change folded into the commit that used to introduce rename_lock-based
variant.  Heads of the branches are byte-for-byte identical:

al@duke:~/linux/trees/vfs$ git log vfs/for-linus|head -1
commit ebc6cb92bfeddf25462842f64604bc9fd2aab5b0
al@duke:~/linux/trees/vfs$ git log vfs/for-linus-2|head -1
commit 8cbf74da435d1bd13dbb790f94c7ff67b2fb6af4
al@duke:~/linux/trees/vfs$ git diff ebc6cb92bfeddf25462842f64604bc9fd2aab5b0 8cbf74da435d1bd13dbb790f94c7ff67b2fb6af4
al@duke:~/linux/trees/vfs$

so testing done on one of them obviously applies to another.  FWIW, on
#for-linus-2 we have
Shortlog:
Al Viro (6):
      lift the "already marked killed" case into shrink_dentry_list()
      split dentry_kill()
      expand dentry_kill(dentry, 0) in shrink_dentry_list()
      shrink_dentry_list(): take parent's ->d_lock earlier
      dealing with the rest of shrink_dentry_list() livelock
      dentry_kill() doesn't need the second argument now

Diffstat:
 fs/dcache.c |  153 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 107 insertions(+), 46 deletions(-)

Linus, how would you prefer it to be handled?