On Fri, Jan 05, 2024 at 03:41:48PM -0500, Vivek Goyal wrote: > On Fri, Jan 05, 2024 at 08:21:00PM +0000, Matthew Wilcox wrote: > > On Fri, Jan 05, 2024 at 03:17:19PM -0500, Vivek Goyal wrote: > > > On Fri, Jan 05, 2024 at 06:53:05PM +0800, Hou Tao wrote: > > > > From: Hou Tao <hout...@huawei.com> > > > > > > > > When invoking virtio_fs_enqueue_req() through kworker, both the > > > > allocation of the sg array and the bounce buffer still use GFP_ATOMIC. > > > > Considering the size of both the sg array and the bounce buffer may be > > > > greater than PAGE_SIZE, use GFP_NOFS instead of GFP_ATOMIC to lower the > > > > possibility of memory allocation failure. > > > > > > > > > > What's the practical benefit of this patch. Looks like if memory > > > allocation fails, we keep retrying at interval of 1ms and don't > > > return error to user space. > > > > You don't deplete the atomic reserves unnecessarily? > > Sounds reasonable. > > With GFP_NOFS specificed, can we still get -ENOMEM? Or this will block > indefinitely till memory can be allocated.
If you need the "loop indefinitely" behaviour, that's GFP_NOFS | __GFP_NOFAIL. If you're actually doing something yourself which can free up memory, this is a bad choice. If you're just sleeping and retrying, you might as well have the MM do that for you.
