From: Andrew Morton <akpm@linux-foundation.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Michal Hocko <mhocko@kernel.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [PATCH v1] drivers/base/memory.c: Don't access uninitialized memmaps in soft_offline_page_store()
Date: Fri, 11 Oct 2019 15:16:34 -0700 [thread overview]
Message-ID: <20191011151634.0b566c9e32e8d0e11181d025@linux-foundation.org> (raw)
In-Reply-To: <20191010141200.8985-1-david@redhat.com>
On Thu, 10 Oct 2019 16:12:00 +0200 David Hildenbrand <david@redhat.com> wrote:
> Uninitialized memmaps contain garbage and in the worst case trigger kernel
> BUGs, especially with CONFIG_PAGE_POISONING. They should not get
> touched.
>
> Right now, when trying to soft-offline a PFN that resides on a memory
> block that was never onlined, one gets a misleading error with
> CONFIG_PAGE_POISONING:
> :/# echo 5637144576 > /sys/devices/system/memory/soft_offline_page
> [ 23.097167] soft offline: 0x150000 page already poisoned
>
> But the actual result depends on the garbage in the memmap.
>
> soft_offline_page() can only work with online pages, it returns -EIO in
> case of ZONE_DEVICE. Make sure to only forward pages that are online
> (iow, managed by the buddy) and, therefore, have an initialized memmap.
>
> Add a check against pfn_to_online_page() and similarly return -EIO.
>
> Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visible after d0dc12e86b319
Should this be cc:stable?
What is the relationship between this and some similar fixes in the
series "mm/memory_hotplug: Shrink zones before removing memory", v6?
Should any of the patches in "mm/memory_hotplug: Shrink zones before
removing memory", v6 be cc:stable?
next prev parent reply other threads:[~2019-10-11 22:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 14:12 [PATCH v1] drivers/base/memory.c: Don't access uninitialized memmaps in soft_offline_page_store() David Hildenbrand
2019-10-11 6:13 ` Naoya Horiguchi
2019-10-11 9:51 ` David Hildenbrand
2019-10-11 22:16 ` Andrew Morton [this message]
2019-10-14 8:30 ` David Hildenbrand
2019-10-14 13:29 ` Michal Hocko
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