Messages in this thread |  | | Date | Sat, 28 Oct 2000 21:25:06 -0200 (BRST) | From | Marcelo Tosatti <> | Subject | Re: tcp_do_sendmsg() allocation still broken ? |
| |
On Sun, 29 Oct 2000, Andi Kleen wrote:
> On Sat, Oct 28, 2000 at 09:13:27PM -0200, Marcelo Tosatti wrote: > > > > > > On Sun, 29 Oct 2000, Andi Kleen wrote: > > > > > On Sat, Oct 28, 2000 at 07:12:44PM -0200, Marcelo Tosatti wrote: > > > > > > > > David, > > > > > > > > tcp_do_sendmsg() still allocates using GFP_KERNEL when it can't, it seems: > > > > > > tcp_do_sendmsg() should only be called from process context, because it can > > > sleep for other reasons anyways. > > > > > > If someone calls it from interrupt context it needs to be fixed. > > > > Andi, > > > > Think about nbd. > > Making tcp_do_sendmsg use GFP_ATOMIC would make it too unreliable for other > situations. Penalizing the whole system just for nbd is not a good idea.
I agree that using GFP_ATOMIC is bad there.
I've fixed 2.2 with GFP_BUFFER.
> > > > > It allocates memory inside its request function, and since we do write > > throttling in try_to_free_pages() we can end up with this deadlock in low > > memory conditions: > > > > nbd_do_request -> nbd_send_req -> nbd_xmit -> sock_sendmsg -> ... -> > > tcp_do_sendmsg -> tcp_send_skb -> skb_copy -> alloc_skb -> > > kmalloc(GFP_KERNEL) -> kmem_cache_grow -> get_free_pages -> > > try_to_free_pages -> shrink_mmap -> try_to_free_buffers -> > > sync_page_buffers -> ll_rw_block -> make_request -> add_request -> > > nbd_do_request -> nbd_send_req -> ... > > > > until there are no more free requests on the request queue and writer > > processes stuck on __get_request_wait. > > Looks like a job for PF_MEMALLOC and making GFP_KERNEL fail earlier.
IMHO GFP_BUFFER is ok.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |