Am 14.09.2018 um 11:22 schrieb Michel Dänzer: > On 2018-09-14 10:22 a.m., Huang Rui wrote: >> On Thu, Sep 13, 2018 at 07:32:24PM +0800, Christian König wrote: >>> Am 13.09.2018 um 10:31 schrieb Huang Rui: >>>> On Wed, Sep 12, 2018 at 09:23:55PM +0200, Christian König wrote: >>>>> While cutting the lists we sometimes accidentally added a list_head from >>>>> the stack to the LRUs, effectively corrupting the list. >>>>> >>>>> Remove the list cutting and use explicit list manipulation instead. >>>> This patch actually fixes the corruption bug. Was it a defect of >>>> list_cut_position or list_splice handlers? >>> We somehow did something illegal with list_cut_position. I haven't >>> narrowed it down till the end, but we ended up with list_heads from the >>> stack to the lru. >> I am confused, in theory, even we do any manipulation with list helper, it >> should not trigger the list corruption. The usage of those helpers should >> ensure the list operation safely... > There's nothing the helpers can do about being passed in pointers to > stack memory. It's a bug in the code using the helpers. Actually I'm not 100% sure of that. To me it looks like we hit a corner case list_cut_position doesn't support. Or we indeed had a logic error in how we called it, anyway the explicit implementation only uses 6 assignments and so is much easier to handle. Christian.
