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Subject: Re: [PATCH v3 07/15] mm/memory_hotplug: Introduce
 offline_and_remove_memory()
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        virtio-dev@lists.oasis-open.org,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
        Oscar Salvador <osalvador@suse.com>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Wei Yang <richard.weiyang@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>, Qian Cai <cai@lca.pw>
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From:   David Hildenbrand <david@redhat.com>
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Message-ID: <2d3b2be0-330e-3e55-7861-b43885349751@redhat.com>
Date:   Thu, 7 May 2020 14:24:11 +0200
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On 07.05.20 14:11, Michael S. Tsirkin wrote:
> On Thu, May 07, 2020 at 01:37:30PM +0200, David Hildenbrand wrote:
>> On 07.05.20 13:34, Michael S. Tsirkin wrote:
>>> On Thu, May 07, 2020 at 01:33:23PM +0200, David Hildenbrand wrote:
>>>>>> I get:
>>>>>>
>>>>>> error: sha1 information is lacking or useless (mm/memory_hotplug.c).
>>>>>> error: could not build fake ancestor
>>>>>>
>>>>>> which version is this against? Pls post patches on top of some tag
>>>>>> in Linus' tree if possible.
>>>>>
>>>>> As the cover states, latest linux-next. To be precise
>>>>>
>>>>> commit 6b43f715b6379433e8eb30aa9bcc99bd6a585f77 (tag: next-20200507,
>>>>> next/master)
>>>>> Author: Stephen Rothwell <sfr@canb.auug.org.au>
>>>>> Date:   Thu May 7 18:11:31 2020 +1000
>>>>>
>>>>>     Add linux-next specific files for 20200507
>>>>>
>>>>
>>>> The patches seem to apply cleanly on top of
>>>>
>>>> commit a811c1fa0a02c062555b54651065899437bacdbe (linus/master)
>>>> Merge: b9388959ba50 16f8036086a9
>>>> Author: Linus Torvalds <torvalds@linux-foundation.org>
>>>> Date:   Wed May 6 20:53:22 2020 -0700
>>>>
>>>>     Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
>>>
>>> Because you have the relevant hashes in your git tree not pruned yet.
>>> Do a new clone and they won't apply.
>>>
>>
>> Yeah, most probably, it knows how to merge. I'm used to sending all my
>> -mm stuff based on -next, so this here is different.
> 
> 
> Documentation/process/5.Posting.rst addresses this:
> 

Thanks for the info.

> 
> Patches must be prepared against a specific version of the kernel.  As a
> general rule, a patch should be based on the current mainline as found in
> Linus's git tree.  When basing on mainline, start with a well-known release
> point - a stable or -rc release - rather than branching off the mainline at
> an arbitrary spot.
> 
> It may become necessary to make versions against -mm, linux-next, or a
> subsystem tree, though, to facilitate wider testing and review.  Depending
> on the area of your patch and what is going on elsewhere, basing a patch
> against these other trees can require a significant amount of work
> resolving conflicts and dealing with API changes.

Yeah, but with -mm patches it is completely impractical to base them
against Linus's git tree.

-- 
Thanks,

David / dhildenb