On Sun, 12 Jan 2020, Tetsuo Handa wrote: > On 2020/01/10 23:11, Vlastimil Babka wrote: > Hmm, this one? Even non-ML destinations are sometimes rejected (e.g. > 554 5.7.1 Service unavailable; Client host [202.181.97.72] blocked using b.barracudacentral.org; http://www.barracudanetworks.com/reputation/?pr=1&ip=202.181.97.72 > ). Anyway, I just worried whether it is really safe to do memory allocation > which might involve memory reclaim. You MM guys know better... We are talking about a call to destroy the kmem_cache. This is not done under any lock. The lock was taken inside that function before the call to list_slab_objects. That can be avoided.