Messages in this thread | | | Date | Wed, 14 Jul 2021 16:29:10 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm/vmalloc: fix wrong behavior in vread |
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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?
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