Re: Please backport shrink dentry list fixes to stable

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Nov 19, 2014 at 07:44:43PM +0100, Holger Hoffstätte wrote:
> On 11/19/14 18:39, Greg KH wrote:
> > On Fri, Oct 03, 2014 at 08:24:34PM +0000, Holger Hoffstätte wrote:
> >>
> >> On Thu, 02 Oct 2014 13:50:24 -0700, Cong Wang wrote:
> >>
> >>> Hello,
> >>>
> >>>
> >>> Sorry to request for backporting another large fixes to stable.
> >>>
> >>> We have seen a list corruption on 3.14 stable kernel (see the end of
> >>> this email), which I think is probably fixed by the following list of
> >>> patches from Al:
> >>>
> >>> fe91522a7ba82ca1a51b07e19954b3825e4aaa22 don't remove from shrink list in select_collect()
> >>> 41edf278fc2f042f4e22a12ed87d19c5201210e1 dentry_kill(): don't try to remove from shrink list
> >>> 01b6035190b024240a43ac1d8e9c6f964f5f1c63 expand the call of dentry_lru_del() in dentry_kill()
> >>> b4f0354e968f5fabd39bc85b99fedae4a97589fe new helper: dentry_free()
> >>> 5c47e6d0ad608987b91affbcf7d1fc12dfbe8fb4 fold try_prune_one_dentry()
> >>> 03b3b889e79cdb6b806fc0ba9be0d71c186bbfaa fold d_kill() and d_free()
> >>>
> >>> And there are 7 patches to fix the above patches:
> >>>
> >>> 00fe425bc28f0ccba034a77783c09c15af4 dcache: add missing lockdep annotation
> >>
> >> This commit does not exist and seems to be the truncated hash of the
> >> last one (9f12600f..). I guess copypasta salad.
> >>
> >>> 8cbf74da435d1bd13dbb790f94c7ff67b2fb6af4 dentry_kill() doesn't need the second argument now
> >>> b2b80195d8829921506880f6dccd21cabd163d0d dealing with the rest of shrink_dentry_list() livelock
> >>> 046b961b45f93a92e4c70525a12f3d378bced130 shrink_dentry_list(): take parent's ->d_lock earlier
> >>> ff2fde9929feb2aef45377ce56b8b12df85dda69 expand dentry_kill(dentry, 0) in shrink_dentry_list()
> >>> e55fd011549eae01a230e3cace6f4d031b6a3453 split dentry_kill()
> >>> 64fd72e0a44bdd62c5ca277cb24d0d02b2d8e9dc lift the "already marked killed" case into shrink_dentry_list()
> >>>
> >>> ...and one more to fix up from Linus:
> >>>
> >>> 9f12600fe425bc28f0ccba034a77783c09c15af4    dcache: add missing lockdep annotation
> >>>
> >>> I don't follow vfs development so could easily miss something here, Al
> >>> should know much better than I do and may come up with a much easier
> >>> way to fix it. Please evaluate this.
> >>
> >> I can confirm that these apply correctly (in reverse order per paragraph) over
> >> 3.14.19 and that it still compiles.
> > 
> > Compiling is nice, what I would like to see is a way to reproduce the
> > original problem and proof that backporting all of these intrusive
> > patches is worth it.  Given that the git commit ids in the list aren't
> > even correct, I'm a bit loath to do so, sorry.
> 
> I should have been more clear - by "still compiles" I meant that it not
> only applies & compiles but also runs and doesn't result in any regressions,
> at least I have not noticed any on my 3 machines.
> 
> As for the hashes: I picked all commits from Linus' main tree and just
> now checked via cgit that e.g. the last commit 64fd72 is exactly where
> it is supposed to be.
> 
> Not sure if that helps..still your call. :)

Ok, I'll consider it for a future 3.14 stable release when things slow
down a bit, right now I have plenty for this next release already.

thanks,

greg k-h