On Mon, Sep 14, 2020 at 07:26:15PM +0530, Pradeep P V K wrote: > Process#1(kswapd) held an inode lock and initaited a writeback to free > the pages, as the inode superblock is fuse, process#2 forms a fuse > request. Process#3 (Fuse daemon threads) while serving process#2 request, > it requires memory(pages) and as the system is already running in low > memory it ends up in calling try_to_ free_pages(), which might now call > kswapd again, which is already stuck with an inode lock held. Thus forms > a deadlock. > > So, remove __GFP_FS flag to avoid allocator recursing into the > filesystem that might already held locks. This is the wrong way to fix the problem. The fuse daemon threads should have called memalloc_nofs_save() as this prevents them from inadvertently tripping over other places where they forgot to use GFP_NOFS (or have no way to pass a GFP_NOFS flags argument).
