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From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>,
	Jianyong Wu <Jianyong.Wu@arm.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Vineet Gupta <vgupta@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-snps-arc@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-mm@kvack.org,
	kexec@lists.infradead.org
Subject: Re: [PATCH v1 2/4] memblock: allow to specify flags with memblock_add_node()
Date: Wed, 29 Sep 2021 18:30:09 +0200	[thread overview]
Message-ID: <3651c7d0-f7b6-63ff-216a-b74176623a6f@redhat.com> (raw)
In-Reply-To: <YVSTkGdh2nQWQp+U@kernel.org>

On 29.09.21 18:25, Mike Rapoport wrote:
> On Mon, Sep 27, 2021 at 05:05:16PM +0200, David Hildenbrand wrote:
>> We want to specify flags when hotplugging memory. Let's prepare to pass
>> flags to memblock_add_node() by adjusting all existing users.
>>
>> Note that when hotplugging memory the system is already up and running
>> and we don't want to add the memory first and apply flags later: it
>> should happen within one memblock call.
> 
> Why is it important that the system is up and why it should happen in a
> single call?
> I don't mind adding flags parameter to memblock_add_node() but this
> changelog does not really explain the reasons to do it.

"After memblock_add_node(), we could race with anybody performing a 
search for MEMBLOCK_NONE, like kexec_file -- and that only happens once 
the system is already up and running. So we want both steps to happen 
atomically."

I can add that to the patch description.

(I think it still won't be completely atomic because memblock isn't 
properly implementing locking yet, but that's a different story)

-- 
Thanks,

David / dhildenb


WARNING: multiple messages have this Message-ID
From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>,
	Jianyong Wu <Jianyong.Wu@arm.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Vineet Gupta <vgupta@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-snps-arc@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-mm@kvack.org,
	kexec@lists.infradead.org
Subject: Re: [PATCH v1 2/4] memblock: allow to specify flags with memblock_add_node()
Date: Wed, 29 Sep 2021 18:30:09 +0200	[thread overview]
Message-ID: <3651c7d0-f7b6-63ff-216a-b74176623a6f@redhat.com> (raw)
In-Reply-To: <YVSTkGdh2nQWQp+U@kernel.org>

On 29.09.21 18:25, Mike Rapoport wrote:
> On Mon, Sep 27, 2021 at 05:05:16PM +0200, David Hildenbrand wrote:
>> We want to specify flags when hotplugging memory. Let's prepare to pass
>> flags to memblock_add_node() by adjusting all existing users.
>>
>> Note that when hotplugging memory the system is already up and running
>> and we don't want to add the memory first and apply flags later: it
>> should happen within one memblock call.
> 
> Why is it important that the system is up and why it should happen in a
> single call?
> I don't mind adding flags parameter to memblock_add_node() but this
> changelog does not really explain the reasons to do it.

"After memblock_add_node(), we could race with anybody performing a 
search for MEMBLOCK_NONE, like kexec_file -- and that only happens once 
the system is already up and running. So we want both steps to happen 
atomically."

I can add that to the patch description.

(I think it still won't be completely atomic because memblock isn't 
properly implementing locking yet, but that's a different story)

-- 
Thanks,

David / dhildenb


_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc

WARNING: multiple messages have this Message-ID
From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>,
	Jianyong Wu <Jianyong.Wu@arm.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Vineet Gupta <vgupta@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-snps-arc@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-mm@kvack.org,
	kexec@lists.infradead.org
Subject: Re: [PATCH v1 2/4] memblock: allow to specify flags with memblock_add_node()
Date: Wed, 29 Sep 2021 18:30:09 +0200	[thread overview]
Message-ID: <3651c7d0-f7b6-63ff-216a-b74176623a6f@redhat.com> (raw)
In-Reply-To: <YVSTkGdh2nQWQp+U@kernel.org>

On 29.09.21 18:25, Mike Rapoport wrote:
> On Mon, Sep 27, 2021 at 05:05:16PM +0200, David Hildenbrand wrote:
>> We want to specify flags when hotplugging memory. Let's prepare to pass
>> flags to memblock_add_node() by adjusting all existing users.
>>
>> Note that when hotplugging memory the system is already up and running
>> and we don't want to add the memory first and apply flags later: it
>> should happen within one memblock call.
> 
> Why is it important that the system is up and why it should happen in a
> single call?
> I don't mind adding flags parameter to memblock_add_node() but this
> changelog does not really explain the reasons to do it.

"After memblock_add_node(), we could race with anybody performing a 
search for MEMBLOCK_NONE, like kexec_file -- and that only happens once 
the system is already up and running. So we want both steps to happen 
atomically."

I can add that to the patch description.

(I think it still won't be completely atomic because memblock isn't 
properly implementing locking yet, but that's a different story)

-- 
Thanks,

David / dhildenb


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2021-09-29 16:30 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 15:05 [PATCH v1 0/4] mm/memory_hotplug: full support for David Hildenbrand
2021-09-27 15:05 ` David Hildenbrand
2021-09-27 15:05 ` David Hildenbrand
2021-09-27 15:05 ` [PATCH v1 1/4] mm/memory_hotplug: handle memblock_add_node() failures in add_memory_resource() David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:05 ` [PATCH v1 2/4] memblock: allow to specify flags with memblock_add_node() David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:19   ` Geert Uytterhoeven
2021-09-27 15:19     ` Geert Uytterhoeven
2021-09-27 15:19     ` Geert Uytterhoeven
2021-09-27 15:19     ` Geert Uytterhoeven
2021-09-28  9:38   ` Heiko Carstens
2021-09-28  9:38     ` Heiko Carstens
2021-09-28  9:38     ` Heiko Carstens
2021-09-29 16:25   ` Mike Rapoport
2021-09-29 16:25     ` Mike Rapoport
2021-09-29 16:25     ` Mike Rapoport
2021-09-29 16:30     ` David Hildenbrand [this message]
2021-09-29 16:30       ` David Hildenbrand
2021-09-29 16:30       ` David Hildenbrand
2021-09-27 15:05 ` [PATCH v1 3/4] memblock: add MEMBLOCK_DRIVER_MANAGED to mimic IORESOURCE_SYSRAM_DRIVER_MANAGED David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-29 16:39   ` Mike Rapoport
2021-09-29 16:39     ` Mike Rapoport
2021-09-29 16:39     ` Mike Rapoport
2021-09-29 16:54     ` David Hildenbrand
2021-09-29 16:54       ` David Hildenbrand
2021-09-29 16:54       ` David Hildenbrand
2021-09-30 21:21       ` Mike Rapoport
2021-09-30 21:21         ` Mike Rapoport
2021-09-30 21:21         ` Mike Rapoport
2021-10-01  8:04         ` David Hildenbrand
2021-10-01  8:04           ` David Hildenbrand
2021-10-01  8:04           ` David Hildenbrand
2021-10-01 14:03           ` Mike Rapoport
2021-10-01 14:03             ` Mike Rapoport
2021-10-01 14:03             ` Mike Rapoport
2021-09-27 15:05 ` [PATCH v1 4/4] mm/memory_hotplug: indicate MEMBLOCK_DRIVER_MANAGED with IORESOURCE_SYSRAM_DRIVER_MANAGED David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:05   ` David Hildenbrand
2021-09-27 15:07 ` [PATCH v1 0/4] mm/memory_hotplug: full support for David Hildenbrand
2021-09-27 15:07   ` David Hildenbrand
2021-09-27 15:07   ` David Hildenbrand

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