On Wed, 26 Feb 2025 06:58:11 -0800 Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Mon, Feb 24, 2025 at 07:33:01PM -0500, Mike Snitzer wrote: > > Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for > > it so nfs_release_folio() can skip calling nfs_wb_folio() from > > kcompactd. > > > > Otherwise NFS can deadlock waiting for kcompactd enduced writeback > > which recurses back to NFS (which triggers writeback to NFSD via > > NFS loopback mount on the same host, NFSD blocks waiting for XFS's > > call to __filemap_get_folio): > > Having a flag for a specific kernel thread feels wrong. Why do you think this? We are getting a bit short of space in tsk->flags. Five PF__HOLE__'s remain. For this patch and for kswapd I guess we could simply record the task_struct*'s in a static array, something like static struct task_struct nice_name[max nodes]; ... if (current == nice_name[my node]) ... It's something we can look at if we start getting really tight on PF_ space.
