On 2016/11/30 8:01, Marc MERLIN wrote: > And, after 5H of copying, not a single hang, or USB disconnect, or anything. > Obviously this seems to point to other problems in the code, and I have no > idea which layer is a culprit here, but reducing the buffers absolutely > helped a lot.
Maybe you can try commit 63f53dea0c9866e9 ("mm: warn about allocations which stall for too long") or http://lkml.kernel.org/r/1478416501-10104-1-git-send-email-penguin-ker...@i-love.sakura.ne.jp for finding the culprit.