Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block

From	Tejun Heo <tj@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block
Date	2017-09-28 16:50 +0200
Message-ID	<uuIit-1KL-3@gated-at.bofh.it> (permalink)
References	<uusdH-8rg-1@gated-at.bofh.it> <uusdH-8rg-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Sep 27, 2017 at 04:35:00PM -0500, Dennis Zhou wrote:
> The iterator functions pcpu_next_md_free_region and
> pcpu_next_fit_region use the block offset to determine if they have
> checked the area in the prior iteration. However, this causes an issue
> when the block offset is greater than subsequent block contig hints. If
> within the iterator it moves to check subsequent blocks, it may fail in
> the second predicate due to the block offset not being cleared. Thus,
> this causes the allocator to skip over blocks leading to false failures
> when allocating from the reserved chunk. While this happens in the
> general case as well, it will only fail if it cannot allocate a new
> chunk.
> 
> This patch resets the block offset to 0 to pass the second predicate
> when checking subseqent blocks within the iterator function.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
> Reported-by: Luis Henriques <lhenriques@suse.com>

Applied to percpu/for-4.14-fixes.

Thanks!

-- 
tejun

Thread

[PATCH 0/2] percpu: fix block iterators and reserved chunk stats Dennis Zhou <dennisszhou@gmail.com> - 2017-09-27 23:40 +0200
  [PATCH 2/2] percpu: fix iteration to prevent skipping over block Dennis Zhou <dennisszhou@gmail.com> - 2017-09-27 23:40 +0200
    Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block Tejun Heo <tj@kernel.org> - 2017-09-28 00:00 +0200
      Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block Luis Henriques <lhenriques@suse.com> - 2017-09-28 10:40 +0200
    Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block Tejun Heo <tj@kernel.org> - 2017-09-28 16:50 +0200
  [PATCH 1/2] percpu: fix starting offset for chunk statistics traversal Dennis Zhou <dennisszhou@gmail.com> - 2017-09-27 23:40 +0200
    Re: [PATCH 1/2] percpu: fix starting offset for chunk statistics  traversal Tejun Heo <tj@kernel.org> - 2017-09-27 23:50 +0200

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