From: David Hildenbrand <david@redhat.com>
To: Alastair D'Silva <alastair@au1.ibm.com>, alastair@d-silva.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Oscar Salvador <osalvador@suse.com>,
Michal Hocko <mhocko@suse.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Dan Williams <dan.j.williams@intel.com>,
Wei Yang <richard.weiyang@gmail.com>, Qian Cai <cai@lca.pw>,
Jason Gunthorpe <jgg@ziepe.ca>,
Logan Gunthorpe <logang@deltatee.com>,
Ira Weiny <ira.weiny@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()
Date: Tue, 17 Sep 2019 09:26:54 +0200 [thread overview]
Message-ID: <d4fbabd0-19ed-a70e-48cc-3fdfcab44841@redhat.com> (raw)
In-Reply-To: <20190917010752.28395-2-alastair@au1.ibm.com>
On 17.09.19 03:07, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
>
> On PowerPC, the address ranges allocated to OpenCAPI LPC memory
> are allocated from firmware. These address ranges may be higher
> than what older kernels permit, as we increased the maximum
> permissable address in commit 4ffe713b7587
> ("powerpc/mm: Increase the max addressable memory to 2PB"). It is
> possible that the addressable range may change again in the
> future.
>
> In this scenario, we end up with a bogus section returned from
> __section_nr (see the discussion on the thread "mm: Trigger bug on
> if a section is not found in __section_nr").
>
> Adding a check here means that we fail early and have an
> opportunity to handle the error gracefully, rather than rumbling
> on and potentially accessing an incorrect section.
>
> Further discussion is also on the thread ("powerpc: Perform a bounds
> check in arch_add_memory").
>
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
> include/linux/memory_hotplug.h | 1 +
> mm/memory_hotplug.c | 13 ++++++++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index f46ea71b4ffd..bc477e98a310 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -110,6 +110,7 @@ extern void __online_page_increment_counters(struct page *page);
> extern void __online_page_free(struct page *page);
>
> extern int try_online_node(int nid);
> +int check_hotplug_memory_addressable(u64 start, u64 size);
>
> extern int arch_add_memory(int nid, u64 start, u64 size,
> struct mhp_restrictions *restrictions);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c73f09913165..02cb9a74f561 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1030,6 +1030,17 @@ int try_online_node(int nid)
> return ret;
> }
>
> +int check_hotplug_memory_addressable(u64 start, u64 size)
> +{
> +#ifdef MAX_PHYSMEM_BITS
> + if ((start + size - 1) >> MAX_PHYSMEM_BITS)
> + return -E2BIG;
> +#endif
> +
> + return 0;
> +}
I guess checking for address space wrapping would be overkill. This
change makes sense for architecture-independent device drivers that make
use of the add/remove memory infrastructure (e.g., virtio-mem I am
working on).
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-09-17 7:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-17 1:07 [PATCH v3 0/2] Add bounds check for Hotplugged memory Alastair D'Silva
2019-09-17 1:07 ` [PATCH v3 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range() Alastair D'Silva
2019-09-17 7:26 ` David Hildenbrand [this message]
2019-09-23 12:25 ` Michal Hocko
2019-09-24 1:31 ` Alastair D'Silva
2019-09-24 9:09 ` Michal Hocko
2019-09-24 9:13 ` David Hildenbrand
2019-09-24 11:45 ` Michal Hocko
2019-09-17 1:07 ` [PATCH v3 2/2] mm: Add a bounds check in devm_memremap_pages() Alastair D'Silva
2019-09-17 7:27 ` David Hildenbrand
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