From: Oscar Salvador <osalvador@suse.de>
To: Shijie Luo <luoshijie1@huawei.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, mhocko@suse.com,
linmiaohe@huawei.com, linfeilong@huawei.com
Subject: Re: [PATCH] mm: mempolicy: fix potential pte_unmap_unlock pte error
Date: Mon, 19 Oct 2020 12:50:34 +0200 [thread overview]
Message-ID: <20201019105029.GA18953@linux> (raw)
In-Reply-To: <20201019074853.50856-1-luoshijie1@huawei.com>
On Mon, Oct 19, 2020 at 03:48:53AM -0400, Shijie Luo wrote:
> When flags in queue_pages_pte_range don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL
> bits, code breaks and passing origin pte - 1 to pte_unmap_unlock seems like
> not a good idea.
I think the above is already explained below?
> queue_pages_pte_range can run in MPOL_MF_MOVE_ALL mode which doesn't migrate
> misplaced pages but returns with EIO when encountering such a page. Since
> commit a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT
> is specified") and early break on the first pte in the range results in
> pte_unmap_unlock on an underflow pte. This can lead to lockups later on when
> somebody tries to lock the pte resp. page_table_lock again..
>
> Fixes: a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when
> MPOL_MF_STRICT is specified")
>
> Signed-off-by: Shijie Luo <luoshijie1@huawei.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Anyway, LGTM:
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2020-10-19 10:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 7:48 Shijie Luo
2020-10-19 10:50 ` Oscar Salvador [this message]
2020-10-19 11:32 ` Michal Hocko
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