On Wed, Feb 28, 2024 at 07:37:58PM +0000, Matthew Wilcox wrote: > On Tue, Feb 27, 2024 at 09:19:47PM +0200, Amir Goldstein wrote: > > On Tue, Feb 27, 2024 at 8:56 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > > > > > Hello! > > > > > > Recent discussions [1] suggest that greater mutual understanding between > > > memory reclaim on the one hand and RCU on the other might be in order. > > > > > > One possibility would be an open discussion. If it would help, I would > > > be happy to describe how RCU reacts and responds to heavy load, along with > > > some ways that RCU's reactions and responses could be enhanced if needed. > > > > > > > Adding fsdevel as this should probably be a cross track session. > > Perhaps broaden this slightly. On the THP Cabal call we just had a > conversation about the requirements on filesystems in the writeback > path. We currently tell filesystem authors that the entire writeback > path must avoid allocating memory in order to prevent deadlock (or use > GFP_MEMALLOC). Is this appropriate? It's a lot of work to assure that > writing pagecache back will not allocate memory in, eg, the network stack, > the device driver, and any other layers the write must traverse. Why would you not simply mark the writeback path with memalloc_nofs_save()?
