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From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: Michal Hocko <mhocko@suse.com>, Mel Gorman <mgorman@techsingularity.net>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Alex Williamson <alex.williamson@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH] mm, thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings
Date: Mon, 17 Sep 2018 11:32:37 +0200	[thread overview]
Message-ID: <87ca7b90-9b84-5722-bd18-a3113c2e20e4@profihost.ag> (raw)
In-Reply-To: <e43348ae-c2db-e327-8dd6-c4f6f0e0cac0@profihost.ag>

May be amissing piece:
vm.overcommit_memory=0

Greets,
Stefan

Am 17.09.2018 um 09:04 schrieb Stefan Priebe - Profihost AG:
> Hi,
> 
> i had multiple memory stalls this weekend again. All kvm processes where
> spinning trying to get > 100% CPU and i was not able to even login to
> ssh. After 5-10 minutes i was able to login.
> 
> There were about 150GB free mem on the host.
> 
> Relevant settings (no local storage involved):
>         vm.dirty_background_ratio:
>             3
>         vm.dirty_ratio:
>             10
>         vm.min_free_kbytes:
>             10567004
> 
> # cat /sys/kernel/mm/transparent_hugepage/defrag
> always defer [defer+madvise] madvise never
> 
> # cat /sys/kernel/mm/transparent_hugepage/enabled
> [always] madvise never
> 
> After that i had the following traces on the host node:
> https://pastebin.com/raw/0VhyQmAv
> 
> Thanks!
> 
> Greets,
> Stefan
> 
> 
> Am 17.09.2018 um 08:11 schrieb Michal Hocko:
>> [sorry I've missed your reply]
>>
>> On Wed 12-09-18 18:29:25, Mel Gorman wrote:
>>> On Wed, Aug 29, 2018 at 09:24:51PM +0200, Michal Hocko wrote:
>> [...]
>>> I recognise that this fix means that users that expect zone_reclaim_mode==1
>>> type behaviour may get burned but the users that benefit from that should
>>> also be users that benefit from sizing their workload to a node. They should
>>> be able to replicate that with mempolicies or at least use prepation scripts
>>> to clear memory on a target node (e.g. membind a memhog to the desired size,
>>> exit and then start the target workload).
>>
>> As I've said in other email. We probably want to add a new mempolicy
>> which has zone_reclaim_mode-like semantic.
>>
>> [...]
>>
>>>> diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
>>>> index 5228c62af416..bac395f1d00a 100644
>>>> --- a/include/linux/mempolicy.h
>>>> +++ b/include/linux/mempolicy.h
>>>> @@ -139,6 +139,8 @@ struct mempolicy *mpol_shared_policy_lookup(struct shared_policy *sp,
>>>>  struct mempolicy *get_task_policy(struct task_struct *p);
>>>>  struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
>>>>  		unsigned long addr);
>>>> +struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
>>>> +						unsigned long addr);
>>>>  bool vma_policy_mof(struct vm_area_struct *vma);
>>>>  
>>>>  extern void numa_default_policy(void);
>>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>>> index c3bc7e9c9a2a..94472bf9a31b 100644
>>>> --- a/mm/huge_memory.c
>>>> +++ b/mm/huge_memory.c
>>>> @@ -629,21 +629,30 @@ 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;
>>>> +	struct mempolicy *pol;
>>>> +
>>>> +#ifdef CONFIG_NUMA
>>>> +	/* __GFP_THISNODE makes sense only if there is no explicit binding */
>>>> +	pol = get_vma_policy(vma, addr);
>>>> +	if (pol->mode != MPOL_BIND)
>>>> +		this_node = __GFP_THISNODE;
>>>> +#endif
>>>>  
>>>
>>> Where is the mpol_cond_put? Historically it might not have mattered
>>> because THP could not be used with a shared possibility but it probably
>>> matters now that tmpfs can be backed by THP.
>>
>> http://lkml.kernel.org/r/20180830064732.GA2656@dhcp22.suse.cz
>>
>>> The comment needs more expansion as well. Arguably it only makes sense in
>>> the event we are explicitly bound to one node because if we are bound to
>>> two nodes without interleaving then why not fall back? The answer to that
>>> is outside the scope of the patch but the comment as-is will cause head
>>> scratches in a years time.
>>
>> Do you have any specific wording in mind? I have a bit hard time to come
>> up with something more precise and do not go into details too much.
>>  
>>>>  	if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
>>>> -		return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
>>>> +		return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY | this_node);
>>>>  	if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
>>>> -		return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
>>>> +		return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM | this_node;
>>>>  	if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
>>>>  		return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
>>>> -							     __GFP_KSWAPD_RECLAIM);
>>>> +							     __GFP_KSWAPD_RECLAIM | this_node);
>>>>  	if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
>>>>  		return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
>>>> -							     0);
>>>> -	return GFP_TRANSHUGE_LIGHT;
>>>> +							     this_node);
>>>> +	return GFP_TRANSHUGE_LIGHT | this_node;
>>>>  }
>>>>  
>>>>  /* Caller must hold page table lock. */
>>>> @@ -715,7 +724,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
>>>>  			pte_free(vma->vm_mm, pgtable);
>>>>  		return ret;
>>>>  	}
>>>> -	gfp = alloc_hugepage_direct_gfpmask(vma);
>>>> +	gfp = alloc_hugepage_direct_gfpmask(vma, haddr);
>>>>  	page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
>>>>  	if (unlikely(!page)) {
>>>>  		count_vm_event(THP_FAULT_FALLBACK);
>>>> @@ -1290,7 +1299,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
>>>>  alloc:
>>>>  	if (transparent_hugepage_enabled(vma) &&
>>>>  	    !transparent_hugepage_debug_cow()) {
>>>> -		huge_gfp = alloc_hugepage_direct_gfpmask(vma);
>>>> +		huge_gfp = alloc_hugepage_direct_gfpmask(vma, haddr);
>>>>  		new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
>>>>  	} else
>>>>  		new_page = NULL;
>>>> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
>>>> index da858f794eb6..75bbfc3d6233 100644
>>>> --- a/mm/mempolicy.c
>>>> +++ b/mm/mempolicy.c
>>>> @@ -1648,7 +1648,7 @@ struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
>>>>   * freeing by another task.  It is the caller's responsibility to free the
>>>>   * extra reference for shared policies.
>>>>   */
>>>> -static struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
>>>> +struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
>>>>  						unsigned long addr)
>>>>  {
>>>>  	struct mempolicy *pol = __get_vma_policy(vma, addr);
>>>> @@ -2026,32 +2026,6 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
>>>>  		goto out;
>>>>  	}
>>>>  
>>>> -	if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
>>>> -		int hpage_node = node;
>>>> -
>>>> -		/*
>>>> -		 * For hugepage allocation and non-interleave policy which
>>>> -		 * allows the current node (or other explicitly preferred
>>>> -		 * node) we only try to allocate from the current/preferred
>>>> -		 * node and don't fall back to other nodes, as the cost of
>>>> -		 * remote accesses would likely offset THP benefits.
>>>> -		 *
>>>> -		 * If the policy is interleave, or does not allow the current
>>>> -		 * node in its nodemask, we allocate the standard way.
>>>> -		 */
>>>> -		if (pol->mode == MPOL_PREFERRED &&
>>>> -						!(pol->flags & MPOL_F_LOCAL))
>>>> -			hpage_node = pol->v.preferred_node;
>>>> -
>>>> -		nmask = policy_nodemask(gfp, pol);
>>>> -		if (!nmask || node_isset(hpage_node, *nmask)) {
>>>> -			mpol_cond_put(pol);
>>>> -			page = __alloc_pages_node(hpage_node,
>>>> -						gfp | __GFP_THISNODE, order);
>>>> -			goto out;
>>>> -		}
>>>> -	}
>>>> -
>>>
>>> The hugepage flag passed into this function is now redundant and that
>>> means that callers of alloc_hugepage_vma need to move back to using
>>> alloc_pages_vma() directly and remove the API entirely. This block of
>>> code is about both GFP flag settings and node selection but at a glance I
>>> cannot see the point of it because it's very similar to the base page code.
>>> The whole point may be to get around the warning in policy_node and that
>>> could just as easily be side-stepped in alloc_hugepage_direct_gfpmask
>>> as you do already in this patch. There should be no reason why THP has a
>>> different policy than a base page within a single VMA.
>>
>> OK, I can follow up with a cleanup patch once we settle down with this
>> approach to fix the issue.
>>
>> Thanks!
>>

  reply	other threads:[~2018-09-17  9:32 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-20  3:22 [PATCH 0/2] fix for "pathological THP behavior" Andrea Arcangeli
2018-08-20  3:22 ` [PATCH 1/2] mm: thp: consolidate policy_nodemask call Andrea Arcangeli
2018-08-20  3:22 ` [PATCH 2/2] mm: thp: fix transparent_hugepage/defrag = madvise || always Andrea Arcangeli
2018-08-20  3:26   ` [PATCH 0/1] fix for "pathological THP behavior" v2 Andrea Arcangeli
2018-08-20  3:26     ` [PATCH 1/1] mm: thp: fix transparent_hugepage/defrag = madvise || always Andrea Arcangeli
2018-08-20 12:35   ` [PATCH 2/2] " Zi Yan
2018-08-20 15:32     ` Andrea Arcangeli
2018-08-21 11:50   ` Michal Hocko
2018-08-21 21:40     ` Andrea Arcangeli
2018-08-22  9:02       ` Michal Hocko
2018-08-22 11:07         ` Michal Hocko
2018-08-22 14:24           ` Andrea Arcangeli
2018-08-22 14:45             ` Michal Hocko
2018-08-22 15:24               ` Andrea Arcangeli
2018-08-23 10:50                 ` Michal Hocko
2018-08-22 15:52         ` Andrea Arcangeli
2018-08-23 10:52           ` Michal Hocko
2018-08-28  7:53             ` Michal Hocko
2018-08-28  8:18               ` Michal Hocko
2018-08-28  8:54                 ` Stefan Priebe - Profihost AG
2018-08-29 11:11                   ` Stefan Priebe - Profihost AG
     [not found]                 ` <D5F4A33C-0A37-495C-9468-D6866A862097@cs.rutgers.edu>
2018-08-29 14:28                   ` Michal Hocko
2018-08-29 14:35                     ` Michal Hocko
2018-08-29 15:22                       ` Zi Yan
2018-08-29 15:47                         ` Michal Hocko
2018-08-29 16:06                           ` Zi Yan
2018-08-29 16:25                             ` Michal Hocko
2018-08-29 19:24                               ` [PATCH] mm, thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings Michal Hocko
2018-08-29 22:54                                 ` Zi Yan
2018-08-30  7:00                                   ` Michal Hocko
2018-08-30 13:22                                     ` Zi Yan
2018-08-30 13:45                                       ` Michal Hocko
2018-08-30 14:02                                         ` Zi Yan
2018-08-30 16:19                                           ` Stefan Priebe - Profihost AG
2018-08-30 16:40                                           ` Michal Hocko
2018-09-05  3:44                                             ` Andrea Arcangeli
2018-09-05  7:08                                               ` Michal Hocko
2018-09-06 11:10                                                 ` Vlastimil Babka
2018-09-06 11:16                                                   ` Vlastimil Babka
2018-09-06 11:25                                                     ` Michal Hocko
2018-09-06 12:35                                                       ` Zi Yan
2018-09-06 10:59                                   ` Vlastimil Babka
2018-09-06 11:17                                     ` Zi Yan
2018-08-30  6:47                                 ` Michal Hocko
2018-09-06 11:18                                   ` Vlastimil Babka
2018-09-06 11:27                                     ` Michal Hocko
2018-09-12 17:29                                 ` Mel Gorman
2018-09-17  6:11                                   ` Michal Hocko
2018-09-17  7:04                                     ` Stefan Priebe - Profihost AG
2018-09-17  9:32                                       ` Stefan Priebe - Profihost AG [this message]
2018-09-17 11:27                                       ` Michal Hocko
2018-08-20 11:58 ` [PATCH 0/2] fix for "pathological THP behavior" Kirill A. Shutemov
2018-08-20 15:19   ` Andrea Arcangeli
2018-08-21 15:30     ` Vlastimil Babka
2018-08-21 17:26       ` David Rientjes
2018-08-21 22:18         ` Andrea Arcangeli
2018-08-21 22:05       ` Andrea Arcangeli
2018-08-22  9:24       ` Michal Hocko
2018-08-22 15:56         ` Andrea Arcangeli
2018-08-20 19:06   ` Yang Shi
2018-08-20 23:24     ` Andrea Arcangeli
2018-09-07 13:05 [PATCH] mm, thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings Michal Hocko
2018-09-08 18:52 ` Stefan Priebe - Profihost AG
2018-09-10  7:39   ` Michal Hocko
2018-09-11  9:03   ` Vlastimil Babka
2018-09-10 20:08 ` David Rientjes
2018-09-10 20:22   ` Stefan Priebe - Profihost AG
2018-09-11  8:51   ` Vlastimil Babka
2018-09-11 11:56   ` Michal Hocko
2018-09-11 20:30     ` David Rientjes
2018-09-12 12:05       ` Michal Hocko
2018-09-12 20:40         ` David Rientjes
2018-09-12 13:54     ` Andrea Arcangeli
2018-09-12 14:21       ` Michal Hocko
2018-09-12 15:25         ` Michal Hocko

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