mm/vmalloc: fix wrong behavior in vread
commit f608788c ("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. The correct way is find the first vmap_are that bigger than target addr, that is what function find_vmap_area_exceed_addr does. Link: https://lkml.kernel.org/r/20210714015959.3204871-1-chenwandun@huawei.com Fixes: f608788c ("mm/vmalloc: use rb_tree instead of list for vread() lookups") Signed-off-by: Chen Wandun <chenwandun@huawei.com> Reported-by: Hulk Robot <hulkci@huawei.com> Cc: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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