From: Alexandre Ghiti <alex@ghiti.fr>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
mpe@ellerman.id.au, Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
"David S . Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v8 4/4] hugetlb: allow to free gigantic pages regardless of the configuration
Date: Wed, 27 Mar 2019 13:54:15 +0100 [thread overview]
Message-ID: <95819dc9-7910-f273-681c-a241fee62dd2@ghiti.fr> (raw)
In-Reply-To: <87pnqcws2u.fsf@linux.ibm.com>
On 03/27/2019 11:05 AM, Aneesh Kumar K.V wrote:
> Alexandre Ghiti <alex@ghiti.fr> writes:
>
>> On 03/27/2019 09:55 AM, Aneesh Kumar K.V wrote:
>>> On 3/27/19 2:14 PM, Alexandre Ghiti wrote:
>>>>
>>>> On 03/27/2019 08:01 AM, Aneesh Kumar K.V wrote:
>>>>> On 3/27/19 12:06 PM, Alexandre Ghiti wrote:
> .....
>
>>> This is now
>>> #define __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
>>> static inline bool gigantic_page_runtime_supported(void)
>>> {
>>> if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
>>> return false;
>>>
>>> return true;
>>> }
>>>
>>>
>>> I am wondering whether it should be
>>>
>>> #define __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
>>> static inline bool gigantic_page_runtime_supported(void)
>>> {
>>>
>>> if (!IS_ENABLED(CONFIG_CONTIG_ALLOC))
>>> return false;
>> I don't think this test should happen here, CONFIG_CONTIG_ALLOC only allows
>> to allocate gigantic pages, doing that check here would prevent powerpc
>> to free boottime gigantic pages when not a guest. Note that this check
>> is actually done in set_max_huge_pages.
>>
>>
>>> if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
>>> return false;
>> Maybe I did not understand this check: I understood that, in the case
>> the system
>> is virtualized, we do not want it to hand back gigantic pages. Does this
>> check
>> test if the system is currently being virtualized ?
>> If yes, I think the patch is correct: it prevents freeing gigantic pages
>> when the system
>> is virtualized but allows a 'normal' system to free gigantic pages.
>>
>>
> Ok double checked the patch applying the the tree. I got confused by the
> removal of that #ifdef. So we now disallow the runtime free by checking
> for gigantic_page_runtime_supported() in __nr_hugepages_store_common.
> Now if we allow and if CONFIG_CONTIG_ALLOC is disabled, we still should
> allow to free the boot time allocated pages back to buddy.
>
> The patch looks good. You can add for the series
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>
> -aneesh
>
Thanks for your time Aneesh,
Alex
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next prev parent reply other threads:[~2019-03-27 12:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-27 6:36 [PATCH v8 0/4] Fix free/allocation of runtime gigantic pages Alexandre Ghiti
2019-03-27 6:36 ` [PATCH v8 1/4] sh: Advertise gigantic page support Alexandre Ghiti
2019-03-27 6:36 ` [PATCH v8 2/4] sparc: " Alexandre Ghiti
2019-03-27 6:36 ` [PATCH v8 3/4] mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC Alexandre Ghiti
2019-03-27 6:36 ` [PATCH v8 4/4] hugetlb: allow to free gigantic pages regardless of the configuration Alexandre Ghiti
2019-03-27 7:01 ` Aneesh Kumar K.V
2019-03-27 8:44 ` Alexandre Ghiti
2019-03-27 8:55 ` Aneesh Kumar K.V
2019-03-27 9:48 ` Alexandre Ghiti
2019-03-27 10:05 ` Aneesh Kumar K.V
2019-03-27 12:54 ` Alexandre Ghiti [this message]
2019-03-28 20:43 ` Mike Kravetz
2019-03-29 6:54 ` Alex Ghiti
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