From: Andrew Morton <akpm@linux-foundation.org>
To: Chen Wandun <chenwandun@huawei.com>
Cc: <serapheim.dimitro@delphix.com>, <urezki@gmail.com>,
<wangkefeng.wang@huawei.com>, <weiyongjun1@huawei.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
Hulk Robot <hulkci@huawei.com>
Subject: Re: [PATCH] mm/vmalloc: fix wrong behavior in vread
Date: Wed, 14 Jul 2021 16:29:10 -0700 [thread overview]
Message-ID: <20210714162910.4cb5434f7745dcf7ce9d85c2@linux-foundation.org> (raw)
In-Reply-To: <20210714015959.3204871-1-chenwandun@huawei.com>
On Wed, 14 Jul 2021 09:59:59 +0800 Chen Wandun <chenwandun@huawei.com> wrote:
> commit f608788cd2d6 ("mm/vmalloc: use rb_tree instead of list for vread()
> lookups") use rb_tree instread of list to speed up lookup, but function
> __find_vmap_area is try to find a vmap_area that include target address,
> if target address is smaller than the leftmost node in vmap_area_root,
> it will return NULL, then vread will read nothing. This behavior is
> different from the primitive semantics.
What is "the primitive semantics"? Does this refer to behaviour prior
to f608788cd2d6?
> The correct way is find the first vmap_are that bigger than target addr,
> that is what function find_vmap_area_exceed_addr does.
Is this problem observable from userspace? If so, what are the effects
and what must an application do to trigger it?
next prev parent reply other threads:[~2021-07-14 23:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 1:59 [PATCH] mm/vmalloc: fix wrong behavior in vread Chen Wandun
2021-07-14 23:29 ` Andrew Morton [this message]
2021-07-15 2:03 ` Chen Wandun
2021-07-15 10:58 ` Uladzislau Rezki
2021-07-15 12:44 ` Chen Wandun
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