| Message ID | 1369599557-22677-1-git-send-email-atomlin@redhat.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On 05/26/2013 04:19 PM, atomlin@redhat.com wrote: > From: Aaron Tomlin <atomlin@redhat.com> > > Since v1: > - Removed unnecessary parentheses > > ---8<--- > > Failed GFP_ATOMIC allocations by the network stack result in dropped > packets, which will be received on a subsequent retransmit, and an > unnecessary, noisy warning with a kernel backtrace. > > These warnings are harmless, but they still cause users to panic and > file bug reports over dropped packets. It would be better to hide the > failed allocation warnings and backtraces, and let retransmits handle > dropped packets quietly. Yes please. Getting memory management bug reports for dropped network packets got old years ago. Lets get rid of those messages. > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello. On 27-05-2013 0:19, atomlin@redhat.com wrote: > From: Aaron Tomlin <atomlin@redhat.com> > Since v1: > - Removed unnecessary parentheses The "changes since version X" section should typically go after --- tearline, else the mainatiner will have to edit your patch before applying. > ---8<--- > Failed GFP_ATOMIC allocations by the network stack result in dropped > packets, which will be received on a subsequent retransmit, and an > unnecessary, noisy warning with a kernel backtrace. > These warnings are harmless, but they still cause users to panic and > file bug reports over dropped packets. It would be better to hide the > failed allocation warnings and backtraces, and let retransmits handle > dropped packets quietly. > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2013-05-27 at 13:39 -0400, Rik van Riel wrote: > On 05/26/2013 04:19 PM, atomlin@redhat.com wrote: > > From: Aaron Tomlin <atomlin@redhat.com> > > > > Since v1: > > - Removed unnecessary parentheses > > > > ---8<--- > > > > Failed GFP_ATOMIC allocations by the network stack result in dropped > > packets, which will be received on a subsequent retransmit, and an > > unnecessary, noisy warning with a kernel backtrace. This claim is wrong, only some protocols deal with retransmits. > > > > These warnings are harmless, but they still cause users to panic and > > file bug reports over dropped packets. It would be better to hide the > > failed allocation warnings and backtraces, and let retransmits handle > > dropped packets quietly. > > Yes please. Getting memory management bug reports for > dropped network packets got old years ago. Lets get > rid of those messages. I am only wondering why this path has anything needing special attention, over thousands of kmalloc() like call sites in the kernel. If mm allocation warnings are useless, just make __GFP_NOWARN the default, and save us thousand of patches (adding the __GFP_NOWARN everywhere) Truth is : some network drivers don't deal very well with allocation errors. mlx4 for example absolutely wants order-2 pages in RX path, with no fallback to order-0 pages. So I am not against this patch, but I can not really acknowledge it, sorry. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/27/2013 06:25 PM, Eric Dumazet wrote: > On Mon, 2013-05-27 at 13:39 -0400, Rik van Riel wrote: >> Yes please. Getting memory management bug reports for >> dropped network packets got old years ago. Lets get >> rid of those messages. > > I am only wondering why this path has anything needing special > attention, over thousands of kmalloc() like call sites in the kernel. There are a few special things about the network code: 1) network packets can arrive extremely fast, in large batches 2) the network code cannot wait for the VM to free memory (GFP_ATOMIC) Other allocations tend to be done less at a time, and/or allow the VM to free up memory before proceeding. > If mm allocation warnings are useless, just make __GFP_NOWARN the > default, and save us thousand of patches (adding the __GFP_NOWARN > everywhere) > > Truth is : some network drivers don't deal very well with allocation > errors. mlx4 for example absolutely wants order-2 pages in RX path, with > no fallback to order-0 pages. Network protocols and network applications tend to deal with packet loss by retransmitting data, though. Also, once all the data from one of those order-2 page buffers has been delivered or forwarded, that buffer becomes available to subsequent network packets. Other allocations tend not to free & reuse their memory as quickly as the network stack. > So I am not against this patch, but I can not really acknowledge it, > sorry. > > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 02139d6..84aa870 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -236,7 +236,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, ? skbuff_fclone_cache : skbuff_head_cache; if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX)) - gfp_mask |= (__GFP_MEMALLOC|__GFP_NOWARN); + gfp_mask |= __GFP_MEMALLOC | __GFP_NOWARN; /* Get the HEAD */ skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);