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!
>>
next prev parent 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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