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Re: [PATCH 2/9 v2] xfs: introduce and use KM_NOLOCKDEP to silence reclaim lockdep false positives

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On Fri 16-12-16 11:37:50, Brian Foster wrote:
> On Fri, Dec 16, 2016 at 04:40:41PM +0100, Michal Hocko wrote:
> > Updated patch after Mike noticed a BUG_ON when KM_NOLOCKDEP is used.
> > ---
> > From 1497e713e11639157aef21cae29052cb3dc7ab44 Mon Sep 17 00:00:00 2001
> > From: Michal Hocko <mhocko@suse.com>
> > Date: Thu, 15 Dec 2016 13:06:43 +0100
> > Subject: [PATCH] xfs: introduce and use KM_NOLOCKDEP to silence reclaim
> >  lockdep false positives
> > 
> > Now that the page allocator offers __GFP_NOLOCKDEP let's introduce
> > KM_NOLOCKDEP alias for the xfs allocation APIs. While we are at it
> > also change KM_NOFS users introduced by b17cb364dbbb ("xfs: fix missing
> > KM_NOFS tags to keep lockdep happy") and use the new flag for them
> > instead. There is really no reason to make these allocations contexts
> > weaker just because of the lockdep which even might not be enabled
> > in most cases.
> > 
> 
> Hi Michal,
> 
> I haven't gone back to fully grok b17cb364dbbb ("xfs: fix missing
> KM_NOFS tags to keep lockdep happy"), so I'm not really familiar with
> the original problem. FWIW, there was another KM_NOFS instance added by
> that commit in xlog_cil_prepare_log_vecs() that is now in
> xlog_cil_alloc_shadow_bufs(). Perhaps Dave can confirm whether the
> original issue still applies..?

Yes, I've noticed that but the reworked code looked sufficiently
different that I didn't dare to simply convert it.
-- 
Michal Hocko
SUSE Labs

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[PATCH 0/9 v2] scope GFP_NOFS api Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:10 +0100
  [PATCH 5/9] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:10 +0100
    Re: [PATCH 5/9] xfs: use memalloc_nofs_{save,restore} instead of  memalloc_noio* Brian Foster <bfoster@redhat.com> - 2016-12-16 17:40 +0100
      [PATCH 5/9 v2] xfs: use memalloc_nofs_{save,restore} instead of  memalloc_noio* Michal Hocko <mhocko@kernel.org> - 2016-12-16 23:10 +0100
  [PATCH 6/9] jbd2: mark the transaction context with the scope GFP_NOFS context Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:10 +0100
    Re: [PATCH 6/9] jbd2: mark the transaction context with the scope  GFP_NOFS context Jan Kara <jack@suse.cz> - 2016-12-19 10:40 +0100
  [PATCH 9/9] Revert "ext4: fix wrong gfp type under transaction" Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:10 +0100
    Re: [PATCH 9/9] Revert "ext4: fix wrong gfp type under transaction" Jan Kara <jack@suse.cz> - 2016-12-19 10:40 +0100
  [PATCH 3/9] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:20 +0100
    Re: [PATCH 3/9] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS Brian Foster <bfoster@redhat.com> - 2016-12-16 17:40 +0100
  [PATCH 7/9] jbd2: make the whole kjournald2 kthread NOFS safe Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:20 +0100
    Re: [PATCH 7/9] jbd2: make the whole kjournald2 kthread NOFS safe Jan Kara <jack@suse.cz> - 2016-12-19 10:40 +0100
  [PATCH 4/9] mm: introduce memalloc_nofs_{save,restore} API Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:20 +0100
  [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence reclaim lockdep false positives Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:20 +0100
    [PATCH 2/9 v2] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Michal Hocko <mhocko@kernel.org> - 2016-12-16 16:50 +0100
      Re: [PATCH 2/9 v2] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Brian Foster <bfoster@redhat.com> - 2016-12-16 17:40 +0100
        Re: [PATCH 2/9 v2] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Michal Hocko <mhocko@kernel.org> - 2016-12-16 23:10 +0100
    Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Dave Chinner <david@fromorbit.com> - 2016-12-19 22:30 +0100
      Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives "Darrick J. Wong" <darrick.wong@oracle.com> - 2016-12-19 23:10 +0100
        Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Dave Chinner <david@fromorbit.com> - 2016-12-20 22:40 +0100
      Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence  reclaim lockdep false positives Michal Hocko <mhocko@kernel.org> - 2016-12-20 09:40 +0100
  [PATCH 1/9] lockdep: allow to disable reclaim lockup detection Michal Hocko <mhocko@kernel.org> - 2016-12-15 15:20 +0100
  [DEBUG PATCH 0/2] debug explicit GFP_NO{FS,IO} usage from the scope context Michal Hocko <mhocko@kernel.org> - 2016-12-16 13:50 +0100
    [DEBUG PATCH 2/2] silent warnings which we cannot do anything about Michal Hocko <mhocko@kernel.org> - 2016-12-16 13:50 +0100
    [DEBUG PATCH 1/2] mm, debug: report when GFP_NO{FS,IO} is used explicitly from memalloc_no{fs,io}_{save,restore} context Michal Hocko <mhocko@kernel.org> - 2016-12-16 13:50 +0100
  Re: [PATCH 0/9 v2] scope GFP_NOFS api Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-12-16 16:20 +0100
    Re: [PATCH 0/9 v2] scope GFP_NOFS api Michal Hocko <mhocko@kernel.org> - 2016-12-16 16:40 +0100
      Re: [PATCH 0/9 v2] scope GFP_NOFS api Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-12-16 17:30 +0100
        Re: [PATCH 0/9 v2] scope GFP_NOFS api Jan Kara <jack@suse.cz> - 2016-12-19 10:30 +0100
  Re: [PATCH 0/9 v2] scope GFP_NOFS api Michal Hocko <mhocko@kernel.org> - 2016-12-22 10:40 +0100

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