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From: "Zi Yan" <zi.yan@cs.rutgers.edu>
To: David Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Argangeli <andrea@kernel.org>,
	Stefan Priebe - Profihost AG <s.priebe@profihost.ag>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 2/2] mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask
Date: Thu, 04 Oct 2018 17:49:47 -0400
Message-ID: <EA62D612-B537-435A-AF5B-96E49E878E0F@cs.rutgers.edu> (raw)
In-Reply-To: <alpine.DEB.2.21.1810041317010.16935@chino.kir.corp.google.com>


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On 4 Oct 2018, at 16:17, David Rientjes wrote:

> On Wed, 26 Sep 2018, Kirill A. Shutemov wrote:
>
>> On Tue, Sep 25, 2018 at 02:03:26PM +0200, Michal Hocko wrote:
>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>> index c3bc7e9c9a2a..c0bcede31930 100644
>>> --- a/mm/huge_memory.c
>>> +++ b/mm/huge_memory.c
>>> @@ -629,21 +629,40 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
>>>   *	    available
>>>   * never: never stall for any thp allocation
>>>   */
>>> -static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
>>> +static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr)
>>>  {
>>>  	const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
>>> +	gfp_t this_node = 0;
>>> +
>>> +#ifdef CONFIG_NUMA
>>> +	struct mempolicy *pol;
>>> +	/*
>>> +	 * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not
>>> +	 * specified, to express a general desire to stay on the current
>>> +	 * node for optimistic allocation attempts. If the defrag mode
>>> +	 * and/or madvise hint requires the direct reclaim then we prefer
>>> +	 * to fallback to other node rather than node reclaim because that
>>> +	 * can lead to excessive reclaim even though there is free memory
>>> +	 * on other nodes. We expect that NUMA preferences are specified
>>> +	 * by memory policies.
>>> +	 */
>>> +	pol = get_vma_policy(vma, addr);
>>> +	if (pol->mode != MPOL_BIND)
>>> +		this_node = __GFP_THISNODE;
>>> +	mpol_cond_put(pol);
>>> +#endif
>>
>> I'm not very good with NUMA policies. Could you explain in more details how
>> the code above is equivalent to the code below?
>>
>
> It breaks mbind() because new_page() is now using numa_node_id() to
> allocate migration targets for instead of using the mempolicy.  I'm not
> sure that this patch was tested for mbind().

I do not see mbind() is broken. With both patches applied, I ran
"numactl -N 0 memhog -r1 4096m membind 1" and saw all pages are allocated
in Node 1 not Node 0, which is returned by numa_node_id().

From the source code, in alloc_pages_vma(), the nodemask is generated
from the memory policy (i.e. mbind in the case above), which only has
the nodes specified by mbind(). Then, __alloc_pages_nodemask() only uses
the zones from the nodemask. The numa_node_id() return value will be
ignored in the actual page allocation process if mbind policy is applied.

Let me know if I miss anything.


--
Best Regards
Yan Zi

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  reply index

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-25 12:03 [PATCH 0/2] thp nodereclaim fixes Michal Hocko
2018-09-25 12:03 ` [PATCH 1/2] mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings Michal Hocko
2018-09-25 12:20   ` Mel Gorman
2018-09-25 12:30     ` Michal Hocko
2018-10-04 20:16   ` David Rientjes
2018-10-04 21:10     ` Andrea Arcangeli
2018-10-04 23:05       ` David Rientjes
2018-10-06  3:19         ` Andrea Arcangeli
2018-10-05  7:38     ` Mel Gorman
2018-10-05 20:35       ` David Rientjes
2018-10-05 23:21         ` Andrea Arcangeli
2018-10-08 20:41           ` David Rientjes
2018-10-09  9:48             ` Mel Gorman
2018-10-09 12:27               ` Michal Hocko
2018-10-09 13:00                 ` Mel Gorman
2018-10-09 14:25                   ` Michal Hocko
2018-10-09 15:16                     ` Mel Gorman
2018-10-09 23:03                     ` Andrea Arcangeli
2018-10-10 21:19                       ` David Rientjes
2018-10-15 22:30                         ` David Rientjes
2018-10-15 22:44                           ` Andrew Morton
2018-10-15 23:19                             ` Andrea Arcangeli
2018-10-22 20:54                               ` David Rientjes
2018-10-16  7:46                             ` Mel Gorman
2018-10-16 22:37                               ` Andrew Morton
2018-10-16 23:11                                 ` Andrea Arcangeli
2018-10-16 23:16                                   ` Andrew Morton
2018-10-17  7:08                                     ` Michal Hocko
2018-10-17  9:00                                 ` Mel Gorman
2018-10-22 21:04                               ` David Rientjes
2018-10-23  1:27                                 ` Zi Yan
2018-10-28 21:45                                   ` David Rientjes
2018-10-23  7:57                                 ` Mel Gorman
2018-10-23  8:38                                   ` Mel Gorman
2018-10-15 22:57                           ` Andrea Arcangeli
2018-10-22 20:45                             ` David Rientjes
2018-10-09 22:17               ` David Rientjes
2018-10-09 22:51                 ` Andrea Arcangeli
2018-10-10  7:54                   ` Vlastimil Babka
2018-10-10 21:00                   ` David Rientjes
2018-10-09 13:08             ` Vlastimil Babka
2018-10-09 22:21             ` Andrea Arcangeli
2018-10-29  5:17   ` Balbir Singh
2018-10-29  9:00     ` Michal Hocko
2018-10-29  9:42       ` Balbir Singh
2018-10-29 10:08         ` Michal Hocko
2018-10-29 10:56           ` Andrea Arcangeli
2018-09-25 12:03 ` [PATCH 2/2] mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask Michal Hocko
2018-09-26 13:30   ` Kirill A. Shutemov
2018-09-26 14:17     ` Michal Hocko
2018-09-26 14:22       ` Michal Hocko
2018-10-19  2:11         ` Andrew Morton
2018-10-19  8:06           ` Michal Hocko
2018-10-22 13:27             ` Vlastimil Babka
2018-10-24 23:17               ` Andrew Morton
2018-10-25  4:56                 ` Vlastimil Babka
2018-10-25 16:14                   ` Michal Hocko
2018-10-25 16:18                     ` Andrew Morton
2018-10-25 16:45                       ` Michal Hocko
2018-10-22 13:15         ` Vlastimil Babka
2018-10-22 13:30           ` Michal Hocko
2018-10-22 13:35             ` Vlastimil Babka
2018-10-22 13:46               ` Michal Hocko
2018-10-22 13:53                 ` Vlastimil Babka
2018-10-04 20:17     ` David Rientjes
2018-10-04 21:49       ` Zi Yan [this message]
2018-10-09 12:36       ` Michal Hocko
2018-09-26 13:08 ` linux-mm@ archive on lore.kernel.org (Was: [PATCH 0/2] thp nodereclaim fixes) Kirill A. Shutemov
2018-09-26 13:14   ` Michal Hocko
2018-09-26 22:22     ` Andrew Morton
2018-09-26 23:08       ` Mel Gorman
2018-09-27  0:47         ` Konstantin Ryabitsev
2018-09-26 15:25   ` Konstantin Ryabitsev
2018-09-27 11:30     ` Kirill A. Shutemov

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