From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org, hca@linux.ibm.com,
catalin.marinas@arm.com, Vasily Gorbik <gor@linux.ibm.com>,
Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 1/3] mm/memory_hotplug: Prevalidate the address range being added with platform
Date: Wed, 20 Jan 2021 12:58:14 +0100 [thread overview]
Message-ID: <20210120115814.GA7107@localhost.localdomain> (raw)
In-Reply-To: <30bbf862-06a4-bd1d-b902-61aa4183b819@redhat.com>
On Wed, Jan 20, 2021 at 11:41:53AM +0100, David Hildenbrand wrote:
> On 20.01.21 09:33, Anshuman Khandual wrote:
> >
> >
> > On 1/19/21 5:51 PM, David Hildenbrand wrote:
> >> On 18.01.21 14:12, Anshuman Khandual wrote:
> >>> This introduces memhp_range_allowed() which can be called in various memory
> >>> hotplug paths to prevalidate the address range which is being added, with
> >>> the platform. Then memhp_range_allowed() calls memhp_get_pluggable_range()
> >>> which provides applicable address range depending on whether linear mapping
> >>> is required or not. For ranges that require linear mapping, it calls a new
> >>> arch callback arch_get_mappable_range() which the platform can override. So
> >>> the new callback, in turn provides the platform an opportunity to configure
> >>> acceptable memory hotplug address ranges in case there are constraints.
> >>>
> >>> This mechanism will help prevent platform specific errors deep down during
> >>> hotplug calls. This drops now redundant check_hotplug_memory_addressable()
> >>> check in __add_pages() but instead adds a VM_BUG_ON() check which would
> >>
> >> In this patch, you keep the __add_pages() checks. But as discussed, we
> >> could perform it in mm/memremap.c:pagemap_range() insted and convert it
> >> to a VM_BUG_ON().
> >
> > Just to be sure, will the following change achieve what you are
> > suggesting here. pagemap_range() after this change, will again
> > be the same like the V1 series.
>
> Yeah, as we used to have in v1. Maybe other reviewers (@Oscar?) have a
> different opinion.
No, I think that placing the check in pagemap_range() out of the if-else
makes much more sense.
Actually, unless my memory fails me that is what I suggested in v2.
I plan to have a look at the series later this week as I am fairly busy
atm.
Thanks
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-01-20 11:58 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 13:12 [PATCH V3 0/3] mm/memory_hotplug: Pre-validate the address range with platform Anshuman Khandual
2021-01-18 13:12 ` [PATCH V3 1/3] mm/memory_hotplug: Prevalidate the address range being added " Anshuman Khandual
2021-01-19 12:21 ` David Hildenbrand
2021-01-20 8:33 ` Anshuman Khandual
2021-01-20 10:41 ` David Hildenbrand
2021-01-20 11:58 ` Oscar Salvador [this message]
2021-01-21 9:23 ` Oscar Salvador
2021-01-22 9:18 ` David Hildenbrand
2021-01-22 10:41 ` Anshuman Khandual
2021-01-22 10:42 ` David Hildenbrand
2021-01-22 10:43 ` David Hildenbrand
2021-01-18 13:13 ` [PATCH V3 2/3] arm64/mm: Define arch_get_mappable_range() Anshuman Khandual
2021-01-19 12:24 ` David Hildenbrand
2021-01-18 13:13 ` [PATCH V3 3/3] s390/mm: " Anshuman Khandual
2021-01-19 12:26 ` David Hildenbrand
2021-01-20 8:28 ` Anshuman Khandual
2021-01-20 10:39 ` David Hildenbrand
2021-01-18 13:13 ` [PATCH RFC] virtio-mem: check against memhp_get_pluggable_range() which memory we can hotplug Anshuman Khandual
2021-01-18 13:21 ` Anshuman Khandual
2021-01-19 12:27 ` David Hildenbrand
2021-01-21 9:57 ` David Hildenbrand
2021-01-22 3:32 ` Anshuman Khandual
2021-01-19 13:33 ` [PATCH V3 0/3] mm/memory_hotplug: Pre-validate the address range with platform David Hildenbrand
2021-01-19 13:40 ` Oscar Salvador
2021-01-20 8:37 ` Anshuman Khandual
2021-01-22 6:04 ` Anshuman Khandual
2021-01-22 8:34 ` David Hildenbrand
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