Re: [PATCH v2] xfs: remove kmem_zalloc_greedy

From	"Luis R. Rodriguez" <mcgrof@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] xfs: remove kmem_zalloc_greedy
Date	2017-03-14 18:00 +0100
Message-ID	<tkXXJ-2UI-23@gated-at.bofh.it> (permalink)
References	<tixO1-76a-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Mar 07, 2017 at 04:35:28PM -0800, Darrick J. Wong wrote:
> The sole remaining caller of kmem_zalloc_greedy is bulkstat, which uses
> it to grab 1-4 pages for staging of inobt records.  The infinite loop in
> the greedy allocation function is causing hangs[1] in generic/269, so
> just get rid of the greedy allocator in favor of kmem_zalloc_large.
> This makes bulkstat somewhat more likely to ENOMEM if there's really no
> pages to spare, but eliminates a source of hangs.
> 
> [1] http://lkml.kernel.org/r/20170301044634.rgidgdqqiiwsmfpj%40XZHOUW.usersys.redhat.com
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: remove single-page fallback
> ---

Since this fixes a hang how about *at the very least* a respective Fixes tag ?
This fixes an existing hang so what are the stable considerations here ? I
realize the answer is not easy but figured its worth asking.

FWIW I trace kmem_zalloc_greedy()'s introduction back to 2006 77e4635ae1917
("[XFS] Add a greedy allocation interface, allocating within a min/max size
range.") through v2.6.19 days...

  Luis

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Re: [PATCH v2] xfs: remove kmem_zalloc_greedy "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-03-14 18:00 +0100
  Re: [PATCH v2] xfs: remove kmem_zalloc_greedy "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-03-14 19:10 +0100
    Re: [PATCH v2] xfs: remove kmem_zalloc_greedy "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-03-15 01:20 +0100
      Re: [PATCH v2] xfs: remove kmem_zalloc_greedy Michal Hocko <mhocko@kernel.org> - 2017-03-15 09:40 +0100
        Re: [PATCH v2] xfs: remove kmem_zalloc_greedy "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-03-15 16:50 +0100
          Re: [PATCH v2] xfs: remove kmem_zalloc_greedy "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-03-15 17:50 +0100

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