From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
David Rientjes <rientjes@google.com>,
Andrea Argangeli <andrea@kernel.org>,
Zi Yan <zi.yan@cs.rutgers.edu>,
Stefan Priebe - Profihost AG <s.priebe@profihost.ag>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask
Date: Mon, 22 Oct 2018 15:15:38 +0200 [thread overview]
Message-ID: <26cb01ff-a094-79f4-7ceb-291e5e053c58@suse.cz> (raw)
In-Reply-To: <20180926142227.GZ6278@dhcp22.suse.cz>
On 9/26/18 4:22 PM, Michal Hocko wrote:
> On Wed 26-09-18 16:17:08, Michal Hocko wrote:
>> On Wed 26-09-18 16:30:39, 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?
>>
>> MPOL_PREFERRED is handled by policy_node() before we call __alloc_pages_nodemask.
>> __GFP_THISNODE is applied only when we are not using
>> __GFP_DIRECT_RECLAIM which is handled in alloc_hugepage_direct_gfpmask
>> now.
>> Lastly MPOL_BIND wasn't handled explicitly but in the end the removed
>> late check would remove __GFP_THISNODE for it as well. So in the end we
>> are doing the same thing unless I miss something
>
> Forgot to add. One notable exception would be that the previous code
> would allow to hit
> WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE));
> in policy_node if the requested node (e.g. cpu local one) was outside of
> the mbind nodemask. This is not possible now. We haven't heard about any
> such warning yet so it is unlikely that it happens though.
I don't think the previous code could hit the warning, as the hugepage
path that would add __GFP_THISNODE didn't call policy_node() (containing
the warning) at all. IIRC early of your patch did hit the warning
though, which is why you added the MPOL_BIND policy check.
next prev parent reply other threads:[~2018-10-22 13:15 UTC|newest]
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 [this message]
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
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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