+Roman Gushchin On Mon, Nov 11, 2019 at 7:47 AM Christopher Lameter <cl@xxxxxxxxx> wrote: > > On Sun, 10 Nov 2019, Yu Zhao wrote: > > > On Sat, Nov 09, 2019 at 11:16:28PM +0000, Christopher Lameter wrote: > > > On Sat, 9 Nov 2019, Yu Zhao wrote: > > > > > > > > struct page *page, *h; > > > > > + unsigned long *map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL); > > > > > + > > > > > + if (!map) > > > > > + return; > > > > > > > > What would happen if we are trying to allocate from the slab that is > > > > being shut down? And shouldn't the allocation be conditional (i.e., > > > > only when CONFIG_SLUB_DEBUG=y)? > > > > > > Kmalloc slabs are never shut down. > > > > Maybe I'm not thinking straight -- isn't it what caused the deadlock in > > the first place? > > Well if kmalloc allocations become a problem then we have numerous > issues all over the kernel to fix. > > > Kmalloc slabs can be shut down when memcg is on. > > Kmalloc needs to work even during shutdown of a memcg. > > Maybe we need to fix memcg to not allocate from the current memcg during > shutdown? > > Roman recently added reparenting of memcg kmem caches on memcg offline and can comment in more detail but we don't shutdown a kmem cache until all the in-fly memcg allocations are resolved. Also the allocation here does not look like a __GFP_ACCOUNT allocation.
