From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, David Hildenbrand <david@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH v1] drivers/base/memory.c: Don't access uninitialized memmaps in soft_offline_page_store()
Date: Thu, 10 Oct 2019 16:12:00 +0200 [thread overview]
Message-ID: <20191010141200.8985-1-david@redhat.com> (raw)
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
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/base/memory.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 6bea4f3f8040..55907c27075b 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -540,6 +540,9 @@ static ssize_t soft_offline_page_store(struct device *dev,
pfn >>= PAGE_SHIFT;
if (!pfn_valid(pfn))
return -ENXIO;
+ /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
+ if (!pfn_to_online_page(pfn))
+ return -EIO;
ret = soft_offline_page(pfn_to_page(pfn), 0);
return ret == 0 ? count : ret;
}
--
2.21.0
next reply other threads:[~2019-10-10 14:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 14:12 David Hildenbrand [this message]
2019-10-11 6:13 ` [PATCH v1] drivers/base/memory.c: Don't access uninitialized memmaps in soft_offline_page_store() Naoya Horiguchi
2019-10-11 9:51 ` David Hildenbrand
2019-10-11 22:16 ` Andrew Morton
2019-10-14 8:30 ` David Hildenbrand
2019-10-14 13:29 ` Michal Hocko
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=20191010141200.8985-1-david@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=rafael@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).