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From: Tejun Heo <tj@kernel.org>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>,
	kexec@lists.infradead.org, Stefan Agner <stefan@agner.ch>,
	Tang Chen <tangchen@cn.fujitsu.com>,
	linux-mm@kvack.org, Yaowei Bai <baiyaowei@cmss.chinamobile.com>,
	Baoquan He <bhe@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
	Pavel Tatashin <pasha.tatashin@oracle.com>,
	linux-acpi@vger.kernel.org, Dave Young <dyoung@redhat.com>,
	Daniel Vacek <neelx@redhat.com>,
	vgoyal@redhat.com, Len Brown <lenb@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Pingfan Liu <kernelfans@gmail.com>,
	yinghai@kernel.org, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Mathieu Malaterre <malat@debian.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr
Date: Thu, 3 Jan 2019 10:47:06 -0800	[thread overview]
Message-ID: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20190102170537.GA3591@rapoport-lnx>

Hello,

On Wed, Jan 02, 2019 at 07:05:38PM +0200, Mike Rapoport wrote:
> I agree that currently the bottom-up allocation after the kernel text has
> issues with KASLR. But this issues are not necessarily related to the
> memory hotplug. Even with a single memory node, a bottom-up allocation will
> fail if KASLR would put the kernel near the end of node0.
> 
> What I am trying to understand is whether there is a fundamental reason to
> prevent allocations from [0, kernel_start)?
> 
> Maybe Tejun can recall why he suggested to start bottom-up allocations from
> kernel_end.

That's from 79442ed189ac ("mm/memblock.c: introduce bottom-up
allocation mode").  I wasn't involved in that patch, so no idea why
the restrictions were added, but FWIW it doesn't seem necessary to me.

Thanks.

-- 
tejun

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WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Baoquan He <bhe@redhat.com>, Pingfan Liu <kernelfans@gmail.com>,
	linux-acpi@vger.kernel.org, linux-mm@kvack.org,
	kexec@lists.infradead.org, Tang Chen <tangchen@cn.fujitsu.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Michal Hocko <mhocko@suse.com>, Jonathan Corbet <corbet@lwn.net>,
	Yaowei Bai <baiyaowei@cmss.chinamobile.com>,
	Pavel Tatashin <pasha.tatashin@oracle.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Daniel Vacek <neelx@redhat.com>,
	Mathieu Malaterre <malat@debian.org>,
	Stefan Agner <stefan@agner.ch>, Dave Young <dyoung@redhat.com>,
	yinghai@kernel.org, vgoyal@redhat.com,
	linux-kernel@vger.kernel.o
Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr
Date: Thu, 3 Jan 2019 10:47:06 -0800	[thread overview]
Message-ID: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20190102170537.GA3591@rapoport-lnx>

Hello,

On Wed, Jan 02, 2019 at 07:05:38PM +0200, Mike Rapoport wrote:
> I agree that currently the bottom-up allocation after the kernel text has
> issues with KASLR. But this issues are not necessarily related to the
> memory hotplug. Even with a single memory node, a bottom-up allocation will
> fail if KASLR would put the kernel near the end of node0.
> 
> What I am trying to understand is whether there is a fundamental reason to
> prevent allocations from [0, kernel_start)?
> 
> Maybe Tejun can recall why he suggested to start bottom-up allocations from
> kernel_end.

That's from 79442ed189ac ("mm/memblock.c: introduce bottom-up
allocation mode").  I wasn't involved in that patch, so no idea why
the restrictions were added, but FWIW it doesn't seem necessary to me.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Baoquan He <bhe@redhat.com>, Pingfan Liu <kernelfans@gmail.com>,
	linux-acpi@vger.kernel.org, linux-mm@kvack.org,
	kexec@lists.infradead.org, Tang Chen <tangchen@cn.fujitsu.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Michal Hocko <mhocko@suse.com>, Jonathan Corbet <corbet@lwn.net>,
	Yaowei Bai <baiyaowei@cmss.chinamobile.com>,
	Pavel Tatashin <pasha.tatashin@oracle.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Daniel Vacek <neelx@redhat.com>,
	Mathieu Malaterre <malat@debian.org>,
	Stefan Agner <stefan@agner.ch>, Dave Young <dyoung@redhat.com>,
	yinghai@kernel.org, vgoyal@redhat.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr
Date: Thu, 3 Jan 2019 10:47:06 -0800	[thread overview]
Message-ID: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20190102170537.GA3591@rapoport-lnx>

Hello,

On Wed, Jan 02, 2019 at 07:05:38PM +0200, Mike Rapoport wrote:
> I agree that currently the bottom-up allocation after the kernel text has
> issues with KASLR. But this issues are not necessarily related to the
> memory hotplug. Even with a single memory node, a bottom-up allocation will
> fail if KASLR would put the kernel near the end of node0.
> 
> What I am trying to understand is whether there is a fundamental reason to
> prevent allocations from [0, kernel_start)?
> 
> Maybe Tejun can recall why he suggested to start bottom-up allocations from
> kernel_end.

That's from 79442ed189ac ("mm/memblock.c: introduce bottom-up
allocation mode").  I wasn't involved in that patch, so no idea why
the restrictions were added, but FWIW it doesn't seem necessary to me.

Thanks.

-- 
tejun

  reply	other threads:[~2019-01-03 18:47 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-28  3:00 [PATCHv3 0/2] mm/memblock: reuse memblock bottom-up allocation style Pingfan Liu
2018-12-28  3:00 ` Pingfan Liu
2018-12-28  3:00 ` [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr Pingfan Liu
2018-12-28  3:00   ` Pingfan Liu
2018-12-31  8:40   ` Mike Rapoport
2018-12-31  8:40     ` Mike Rapoport
2019-01-02  6:47     ` Pingfan Liu
2019-01-02  9:27       ` Mike Rapoport
2019-01-02 10:18         ` Baoquan He
2019-01-02 17:05           ` Mike Rapoport
2019-01-02 17:05             ` Mike Rapoport
2019-01-03 18:47             ` Tejun Heo [this message]
2019-01-03 18:47               ` Tejun Heo
2019-01-03 18:47               ` Tejun Heo
2019-01-04 15:09               ` Mike Rapoport
2019-01-04 15:09                 ` Mike Rapoport
2019-01-04 15:09                 ` Mike Rapoport
2019-01-05  3:44                 ` Baoquan He
2019-01-05  3:44                   ` Baoquan He
2019-01-06  6:27                   ` Mike Rapoport
2019-01-06  6:27                     ` Mike Rapoport
2019-01-08  8:50                     ` Baoquan He
2019-01-08  8:50                       ` Baoquan He
2019-01-07  8:37               ` Pingfan Liu
2019-01-07  8:37                 ` Pingfan Liu
2019-01-04  5:59           ` Pingfan Liu
2019-01-04  5:59             ` Pingfan Liu
2019-01-04 16:20             ` Mike Rapoport
2019-01-04 16:20               ` Mike Rapoport
2018-12-28  3:00 ` [PATCHv3 2/2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Pingfan Liu
2018-12-28  3:00   ` Pingfan Liu
2018-12-31  8:46   ` Mike Rapoport
2018-12-31  8:46     ` Mike Rapoport
2018-12-31  8:46     ` Mike Rapoport
2019-01-02  6:47     ` Pingfan Liu
2019-01-02  9:28       ` Mike Rapoport
2018-12-28  3:39 ` [PATCHv3 0/2] mm/memblock: reuse memblock bottom-up allocation style Baoquan He
2018-12-28  3:39   ` Baoquan He

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