On Mon, Apr 12, 2021 at 10:05 PM Guenter Roeck <li...@roeck-us.net> wrote: > > On 4/12/21 10:38 AM, Eric Dumazet wrote: > [ ... ] > > > Yes, I think this is the real issue here. This smells like some memory > > corruption. > > > > In my traces, packet is correctly received in AF_PACKET queue. > > > > I have checked the skb is well formed. > > > > But the user space seems to never call poll() and recvmsg() on this > > af_packet socket. > > > > After sprinkling the kernel with debug messages: > > 424 00:01:33.674181 sendto(6, > "E\0\1H\0\0\0\0@\21y\246\0\0\0\0\377\377\377\377\0D\0C\00148\346\1\1\6\0\246\336\333\v\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0RT\0\ > 424 00:01:33.693873 close(6) = 0 > 424 00:01:33.694652 fcntl64(5, F_SETFD, FD_CLOEXEC) = 0 > 424 00:01:33.695213 clock_gettime64(CLOCK_MONOTONIC, 0x7be18a18) = -1 > EFAULT (Bad address) > 424 00:01:33.695889 write(2, "udhcpc: clock_gettime(MONOTONIC) failed\n", > 40) = -1 EFAULT (Bad address) > 424 00:01:33.697311 exit_group(1) = ? > 424 00:01:33.698346 +++ exited with 1 +++ > > I only see that after adding debug messages in the kernel, so I guess there > must be > a heisenbug somehere. > > Anyway, indeed, I see (another kernel debug message): > > __do_sys_clock_gettime: Returning -EFAULT on address 0x7bacc9a8 > > So udhcpc doesn't even try to read the reply because it crashes after sendto() > when trying to read the current time. Unless I am missing something, that > means > that the problem happens somewhere on the send side. > > To make things even more interesting, it looks like the failing system call > isn't always clock_gettime(). > > Guenter
I think GRO fast path has never worked on SUPERH. Probably SUPERH has never used a fast NIC (10Gbit+) The following hack fixes the issue. diff --git a/net/core/dev.c b/net/core/dev.c index af8c1ea040b9364b076e2d72f04dc3de2d7e2f11..91ba89a645ff91d4cd4f3d8dc8a009bcb67da344 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5916,13 +5916,16 @@ static struct list_head *gro_list_prepare(struct napi_struct *napi, static void skb_gro_reset_offset(struct sk_buff *skb) { +#if !defined(CONFIG_SUPERH) const struct skb_shared_info *pinfo = skb_shinfo(skb); const skb_frag_t *frag0 = &pinfo->frags[0]; +#endif NAPI_GRO_CB(skb)->data_offset = 0; NAPI_GRO_CB(skb)->frag0 = NULL; NAPI_GRO_CB(skb)->frag0_len = 0; +#if !defined(CONFIG_SUPERH) if (!skb_headlen(skb) && pinfo->nr_frags && !PageHighMem(skb_frag_page(frag0))) { NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0); @@ -5930,6 +5933,7 @@ static void skb_gro_reset_offset(struct sk_buff *skb) skb_frag_size(frag0), skb->end - skb->tail); } +#endif } static void gro_pull_from_frag0(struct sk_buff *skb, int grow)