On Thu, Sep 29, 2022 at 09:40:10AM +0200, Stefano Garzarella wrote: > On Wed, Sep 28, 2022 at 04:02:12PM -0400, Michael S. Tsirkin wrote: > > On Wed, Sep 28, 2022 at 05:11:35PM +0200, Stefano Garzarella wrote: > > > On Wed, Sep 28, 2022 at 05:31:58AM -0400, Michael S. Tsirkin wrote: > > > > On Wed, Sep 28, 2022 at 10:28:23AM +0200, Stefano Garzarella wrote: > > > > > On Wed, Sep 28, 2022 at 03:45:38PM +0900, Junichi Uekawa wrote: > > > > > > When copying a large file over sftp over vsock, data size is usually 32kB, > > > > > > and kmalloc seems to fail to try to allocate 32 32kB regions. > > > > > > > > > > > > Call Trace: > > > > > > [<ffffffffb6a0df64>] dump_stack+0x97/0xdb > > > > > > [<ffffffffb68d6aed>] warn_alloc_failed+0x10f/0x138 > > > > > > [<ffffffffb68d868a>] ? __alloc_pages_direct_compact+0x38/0xc8 > > > > > > [<ffffffffb664619f>] __alloc_pages_nodemask+0x84c/0x90d > > > > > > [<ffffffffb6646e56>] alloc_kmem_pages+0x17/0x19 > > > > > > [<ffffffffb6653a26>] kmalloc_order_trace+0x2b/0xdb > > > > > > [<ffffffffb66682f3>] __kmalloc+0x177/0x1f7 > > > > > > [<ffffffffb66e0d94>] ? copy_from_iter+0x8d/0x31d > > > > > > [<ffffffffc0689ab7>] vhost_vsock_handle_tx_kick+0x1fa/0x301 [vhost_vsock] > > > > > > [<ffffffffc06828d9>] vhost_worker+0xf7/0x157 [vhost] > > > > > > [<ffffffffb683ddce>] kthread+0xfd/0x105 > > > > > > [<ffffffffc06827e2>] ? vhost_dev_set_owner+0x22e/0x22e [vhost] > > > > > > [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3 > > > > > > [<ffffffffb6eb332e>] ret_from_fork+0x4e/0x80 > > > > > > [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3 > > > > > > > > > > > > Work around by doing kvmalloc instead. > > > > > > > > > > > > Signed-off-by: Junichi Uekawa <uekawa@xxxxxxxxxxxx> > > > > > > > > My worry here is that this in more of a work around. > > > > It would be better to not allocate memory so aggressively: > > > > if we are so short on memory we should probably process > > > > packets one at a time. Is that very hard to implement? > > > > > > Currently the "virtio_vsock_pkt" is allocated in the "handle_kick" callback > > > of TX virtqueue. Then the packet is multiplexed on the right socket queue, > > > then the user space can de-queue it whenever they want. > > > > > > So maybe we can stop processing the virtqueue if we are short on memory, but > > > when can we restart the TX virtqueue processing? > > > > Assuming you added at least one buffer, the time to restart would be > > after that buffer has been used. > > Yes, but we still might not have as many continuous pages to allocate, so I > would use kvmalloc the same. you would do something like if (is_vmalloc_addr()) stop adding buffers. > I agree that we should do better, I hope that moving to sk_buff will allow > us to better manage allocation. Maybe after we merge that part we should > spend some time to solve these problems. > > Thanks, > Stefano
