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Subject: Re: [patch for-4.20] Revert "mm, thp: consolidate THP gfp handling
 into alloc_hugepage_direct_gfpmask"
To:     David Rientjes <rientjes@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Andrea Arcangeli <aarcange@redhat.com>,
        mgorman@techsingularity.net, mhocko@kernel.org,
        ying.huang@intel.com, s.priebe@profihost.ag,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        alex.williamson@redhat.com, lkp@01.org, kirill@shutemov.name,
        Andrew Morton <akpm@linux-foundation.org>,
        zi.yan@cs.rutgers.edu
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From:   Vlastimil Babka <vbabka@suse.cz>
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Date:   Fri, 7 Dec 2018 15:41:49 +0100
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On 12/6/18 11:00 PM, David Rientjes wrote:
> This reverts commit 89c83fb539f95491be80cdd5158e6f0ce329e317.
> 
> There are a couple of issues with 89c83fb539f9 independent of its partial 
> revert in 2f0799a0ffc0 ("mm, thp: restore node-local hugepage 
> allocations"):
> 
> Firstly, the interaction between alloc_hugepage_direct_gfpmask() and 
> alloc_pages_vma() is racy wrt __GFP_THISNODE and MPOL_BIND.  
> alloc_hugepage_direct_gfpmask() makes sure not to set __GFP_THISNODE for 
> an MPOL_BIND policy but the policy used in alloc_pages_vma() may not be 
> the same for shared vma policies, triggering the WARN_ON_ONCE() in 
> policy_node().

AFAICS 2f0799a0ffc0 removed the policy check in
alloc_hugepage_direct_gfpmask() comlpetely, so it's not racy and the
warning will always trigger for a MPOL_BIND policy right now?