From: Andrew Morton <akpm@linux-foundation.org>
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Rik van Riel <riel@redhat.com>,
Fengguang Wu <fengguang.wu@intel.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
David Rientjes <rientjes@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Jiri Kosina <jkosina@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/4] mm/pgtable: Fix continue to preallocate pmds even if failure occurrence
Date: Tue, 20 Aug 2013 17:18:16 -0700 [thread overview]
Message-ID: <20130820171816.1b759e87.akpm@linux-foundation.org> (raw)
In-Reply-To: <5213fe45.660c420a.4066.ffffd8c7SMTPIN_ADDED_BROKEN@mx.google.com>
On Wed, 21 Aug 2013 07:39:35 +0800 Wanpeng Li <liwanp@linux.vnet.ibm.com> wrote:
> >Nope. If the error path is taken, free_pmds() will free uninitialised
> >items from pmds[], which is a local in pgd_alloc() and contains random
> >stack junk. The kernel will crash.
> >
> >You could pass an nr_pmds argument to free_pmds(), or zero out the
> >remaining items on the error path. However, although the current code
> >is a bit kooky, I don't see that it is harmful in any way.
> >
>
> There is a check in free_pmds():
>
> if (pmds[i])
> free_page((unsigned long)pmds[i]);
>
> which will avoid the issue you mentioned.
pmds[i] is uninitialized. It gets allocated
on the stack in pgd_alloc() and does not get zeroed.
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prev parent reply other threads:[~2013-08-21 0:18 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-20 6:54 Wanpeng Li
2013-08-20 6:54 ` [PATCH v2 2/4] mm/sparse: introduce alloc_usemap_and_memmap Wanpeng Li
2013-08-20 23:07 ` Andrew Morton
2013-08-21 0:02 ` Yinghai Lu
2013-08-21 3:11 ` Wanpeng Li
2013-08-21 3:11 ` Wanpeng Li
[not found] ` <52142ffe.84c0440a.57e5.02acSMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-21 4:28 ` Yinghai Lu
2013-08-21 7:29 ` Wanpeng Li
2013-08-21 7:29 ` Wanpeng Li
[not found] ` <52146c58.a3e2440a.0f5a.ffffed8dSMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-22 5:19 ` Yinghai Lu
2013-08-22 12:08 ` Wanpeng Li
2013-08-22 12:08 ` Wanpeng Li
2013-08-22 12:14 ` Wanpeng Li
2013-08-22 12:14 ` Wanpeng Li
[not found] ` <521600cc.22ab440a.2703.53f1SMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-29 2:18 ` Yinghai Lu
2013-08-29 2:34 ` Yinghai Lu
2013-08-29 2:42 ` Yinghai Lu
2013-08-29 2:51 ` Wanpeng Li
2013-08-29 2:51 ` Wanpeng Li
[not found] ` <521eb73e.e3bf420a.2ad0.09c2SMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-29 4:10 ` Yinghai Lu
2013-08-29 5:32 ` Wanpeng Li
2013-08-29 5:32 ` Wanpeng Li
2013-08-20 6:54 ` [PATCH v2 3/4] mm/writeback: make writeback_inodes_wb static Wanpeng Li
2013-08-20 16:01 ` Seth Jennings
2013-08-20 6:54 ` [PATCH v2 4/4] mm/vmalloc: use wrapper function get_vm_area_size to caculate size of vm area Wanpeng Li
2013-08-20 16:03 ` Seth Jennings
2013-08-20 16:00 ` [PATCH v2 1/4] mm/pgtable: Fix continue to preallocate pmds even if failure occurrence Seth Jennings
2013-08-20 23:04 ` Andrew Morton
2013-08-20 23:39 ` Wanpeng Li
2013-08-20 23:39 ` Wanpeng Li
[not found] ` <5213fe45.660c420a.4066.ffffd8c7SMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-21 0:18 ` Andrew Morton [this message]
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