From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
David Hildenbrand <david@redhat.com>,
linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/5] mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions
Date: Tue, 12 Jan 2021 12:00:28 +0100 [thread overview]
Message-ID: <20210112110028.GB12956@linux> (raw)
In-Reply-To: <161044409294.1482714.434561066315039753.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, Jan 12, 2021 at 01:34:53AM -0800, Dan Williams wrote:
> While pfn_to_online_page() is able to determine pfn_valid() at
> subsection granularity it is not able to reliably determine if a given
> pfn is also online if the section is mixes ZONE_{NORMAL,MOVABLE} with
> ZONE_DEVICE. This means that pfn_to_online_page() may return invalid
> @page objects. For example with a memory map like:
>
> 100000000-1fbffffff : System RAM
> 142000000-143002e16 : Kernel code
> 143200000-143713fff : Kernel rodata
> 143800000-143b15b7f : Kernel data
> 144227000-144ffffff : Kernel bss
> 1fc000000-2fbffffff : Persistent Memory (legacy)
> 1fc000000-2fbffffff : namespace0.0
>
> This command:
>
> echo 0x1fc000000 > /sys/devices/system/memory/soft_offline_page
>
> ...succeeds when it should fail. When it succeeds it touches
> an uninitialized page and may crash or cause other damage (see
> dissolve_free_huge_page()).
[...]
> Because the collision case is rare, and for simplicity, the
> SECTION_TAINT_ZONE_DEVICE flag is never cleared once set.
>
> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Reported-by: Michal Hocko <mhocko@suse.com>
> Reported-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
WARNING: multiple messages have this Message-ID (diff)
From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
David Hildenbrand <david@redhat.com>,
vishal.l.verma@intel.com, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/5] mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions
Date: Tue, 12 Jan 2021 12:00:28 +0100 [thread overview]
Message-ID: <20210112110028.GB12956@linux> (raw)
In-Reply-To: <161044409294.1482714.434561066315039753.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, Jan 12, 2021 at 01:34:53AM -0800, Dan Williams wrote:
> While pfn_to_online_page() is able to determine pfn_valid() at
> subsection granularity it is not able to reliably determine if a given
> pfn is also online if the section is mixes ZONE_{NORMAL,MOVABLE} with
> ZONE_DEVICE. This means that pfn_to_online_page() may return invalid
> @page objects. For example with a memory map like:
>
> 100000000-1fbffffff : System RAM
> 142000000-143002e16 : Kernel code
> 143200000-143713fff : Kernel rodata
> 143800000-143b15b7f : Kernel data
> 144227000-144ffffff : Kernel bss
> 1fc000000-2fbffffff : Persistent Memory (legacy)
> 1fc000000-2fbffffff : namespace0.0
>
> This command:
>
> echo 0x1fc000000 > /sys/devices/system/memory/soft_offline_page
>
> ...succeeds when it should fail. When it succeeds it touches
> an uninitialized page and may crash or cause other damage (see
> dissolve_free_huge_page()).
[...]
> Because the collision case is rare, and for simplicity, the
> SECTION_TAINT_ZONE_DEVICE flag is never cleared once set.
>
> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Reported-by: Michal Hocko <mhocko@suse.com>
> Reported-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-01-12 11:00 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 9:34 [PATCH v2 0/5] mm: Fix pfn_to_online_page() with respect to ZONE_DEVICE Dan Williams
2021-01-12 9:34 ` Dan Williams
2021-01-12 9:34 ` [PATCH v2 1/5] mm: Move pfn_to_online_page() out of line Dan Williams
2021-01-12 9:34 ` Dan Williams
2021-01-12 9:46 ` David Hildenbrand
2021-01-12 9:46 ` David Hildenbrand
2021-01-12 10:19 ` Oscar Salvador
2021-01-12 10:19 ` Oscar Salvador
2021-01-12 9:34 ` [PATCH v2 2/5] mm: Teach pfn_to_online_page() to consider subsection validity Dan Williams
2021-01-12 9:34 ` Dan Williams
2021-01-12 9:53 ` David Hildenbrand
2021-01-12 9:53 ` David Hildenbrand
2021-01-12 10:48 ` Oscar Salvador
2021-01-12 10:48 ` Oscar Salvador
2021-01-12 22:20 ` Dan Williams
2021-01-12 22:20 ` Dan Williams
2021-01-12 9:34 ` [PATCH v2 3/5] mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions Dan Williams
2021-01-12 9:34 ` Dan Williams
2021-01-12 10:01 ` David Hildenbrand
2021-01-12 10:01 ` David Hildenbrand
2021-01-12 11:00 ` Oscar Salvador [this message]
2021-01-12 11:00 ` Oscar Salvador
2021-01-12 9:34 ` [PATCH v2 4/5] mm: Fix page reference leak in soft_offline_page() Dan Williams
2021-01-12 9:34 ` Dan Williams
2021-01-12 9:53 ` Oscar Salvador
2021-01-12 9:53 ` Oscar Salvador
2021-01-12 20:03 ` Dan Williams
2021-01-12 20:03 ` Dan Williams
2021-01-12 10:16 ` David Hildenbrand
2021-01-12 10:16 ` David Hildenbrand
2021-01-12 9:35 ` [PATCH v2 5/5] libnvdimm/namespace: Fix visibility of namespace resource attribute Dan Williams
2021-01-12 9:35 ` Dan Williams
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210112110028.GB12956@linux \
--to=osalvador@suse.de \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=david@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nvdimm@lists.01.org \
--cc=mhocko@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.