linux-kernel - RE: [PATCH] pstore: Solve lockdep warning by moving inode locks

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Date:   Tue, 2 May 2017 10:10:18 +0000
From:   "Lofstedt, Marta" <marta.lofstedt@...el.com>
To:     Kees Cook <keescook@...omium.org>
CC:     Chris Wilson <chris@...is-wilson.co.uk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Anton Vorontsov <anton@...msg.org>,
        "Colin Cross" <ccross@...roid.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        Namhyung Kim <namhyung@...nel.org>
Subject: RE: [PATCH] pstore: Solve lockdep warning by moving inode locks



> -----Original Message-----
> From: keescook@...gle.com [mailto:keescook@...gle.com] On Behalf Of
> Kees Cook
> Sent: Friday, April 28, 2017 10:22 PM
> To: Lofstedt, Marta <marta.lofstedt@...el.com>
> Cc: Chris Wilson <chris@...is-wilson.co.uk>; linux-kernel@...r.kernel.org;
> Anton Vorontsov <anton@...msg.org>; Colin Cross <ccross@...roid.com>;
> Luck, Tony <tony.luck@...el.com>; Namhyung Kim <namhyung@...nel.org>
> Subject: Re: [PATCH] pstore: Solve lockdep warning by moving inode locks
> 
> On Fri, Apr 28, 2017 at 2:00 AM, Lofstedt, Marta <marta.lofstedt@...el.com>
> wrote:
> >
> >
> >> -----Original Message-----
> >> From: Chris Wilson [mailto:chris@...is-wilson.co.uk]
> >> Sent: Friday, April 28, 2017 10:53 AM
> >> To: Kees Cook <keescook@...omium.org>
> >> Cc: linux-kernel@...r.kernel.org; Anton Vorontsov
> <anton@...msg.org>;
> >> Colin Cross <ccross@...roid.com>; Luck, Tony <tony.luck@...el.com>;
> >> Lofstedt, Marta <marta.lofstedt@...el.com>; Namhyung Kim
> >> <namhyung@...nel.org>
> >> Subject: Re: [PATCH] pstore: Solve lockdep warning by moving inode
> >> locks
> >>
> >> On Thu, Apr 27, 2017 at 04:20:37PM -0700, Kees Cook wrote:
> >> > Lockdep complains about a possible deadlock between mount and
> >> > unlink (which is technically impossible), but fixing this improves
> >> > possible future multiple-backend support, and keeps locking in the right
> order.
> >>
> >> I have merged your for-next/pstore branch (which included this patch,
> >> so I hope I chose correctly ;) into our CI. That should exercise it
> >> on the machines that we originally found the lockdep splat.
> 
> That's the branch, yes, thanks!
> 
> >>
> >> Thanks,
> >> -Chris
> >>
> >
> > Chris, I tested this on drm-tip after you merged for-next/pstore.
> > EFI_VARS_PSTORE is enabled.
> > I deliberately cause kernel panic and reboot, but unfortunately that kernel
> doesn't reboot properly. On display I see a bunch of:
> > "Cleaning orphaned inode ...", but then kernel boot  is stuck.
> > I run this on a BDW NUCi5, which I have been using successfully with
> pstore-efi for weeks.
> > Fortunately I had some other pstore enabled kernels, so if I clean out
> /sys/fs/pstore/* with one of them I can boot above kernel again.
> 
> Hrmm... if you isolate this down to a different pstore issue, please let me
> know. I haven't seen filesystem corruption in my tests yet. :P
> 
> Thanks for testing!
> 
> -Kees


Hi Kees,

I can't reproduce above issue with your:
"
  git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git tags/pstore-v4.12-rc1

for you to fetch changes up to 3a7d2fd16c57a1ef47dc2891171514231c9c7c6e:

  pstore: Solve lockdep warning by moving inode locks (2017-04-27 20:35:34 -0700)"


BR,
Marta
 

> 
> --
> Kees Cook
> Pixel Security