On Thu, Apr 08, 2021 at 07:28:01AM +0800, Wang Yugui wrote: > Hi, > > > > > > upper caller: > > > > > nofs_flag = memalloc_nofs_save(); > > > > > ret = btrfs_drew_lock_init(&root->snapshot_lock); > > > > > memalloc_nofs_restore(nofs_flag); > > > > The issue is here. nofs is set which means percpu attempts an atomic > > allocation. If it cannot find anything already allocated it isn't happy. > > This was done before memalloc_nofs_{save/restore}() were pervasive. > > > > Percpu should probably try to allocate some pages if possible even if > > nofs is set. > > Thanks. > > I will wait for the patch, and then test it. >
I'm currently a bit busy with some other things. Adding support I don't think will be much work, just a little bit tricky. I recommend carrying what you have minus the change to reserved percpu memory for now. If I'm the one to write it, I'll cc you. Thanks, Dennis