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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?aZ+heZ8+iCoALK1PkcMOJrNcwwEqQCX/x9E9aN1MpcBTAqFFqDROnf6Xy8?= =?iso-8859-1?Q?fb/SBMnwZtEKnfNsKtx8ubsHAUEsxvJHn84+ciUGm7fGSqtll0TkAHNnGk?= =?iso-8859-1?Q?2JSapN01L4q2nrGblX7qhaNW3PP0Ap4Dl6PkP4JJL6ohd0orwLOxWfY2iW?= =?iso-8859-1?Q?4X2aJIXGDjVIy41iUhETthYQylws50M81gEnwNIlCJSEon8p8RA4Yzx6s5?= =?iso-8859-1?Q?Oi7UzhDEMl3sEkcnKVt0XIpE9oBoI5gEBGy/muEj6WGhexsUAQ+TEtGxD1?= =?iso-8859-1?Q?lvFiwASmK7U9I7vnti8TqAHzU/8Z/TWSyc5dPImLLJ3EG8DX+P6MHRJErg?= =?iso-8859-1?Q?NOF020rLZc14Cnj6i8ZFR3+vpCFPG+kistW+19uwI5fEfzV2Pv7uV3JxQz?= =?iso-8859-1?Q?h58YXtWgO/gHQMAMT/cUQmydNlj+PffS7SUEDTlvmQxJytoqevYMoObfAC?= =?iso-8859-1?Q?WotT0L2WyMEPCNb3qn4PUpLLlhbDUqf3YqXSENvsW2jw1cQvV6RvXEmR8J?= =?iso-8859-1?Q?MEuC6WZTSj8Iw+qA+/pDM+YbMS8rbzIdrF+mnzT1P0ua6/BQDlYjtq79/b?= =?iso-8859-1?Q?Qk+mEfuc3g/Nn06dqNCc53z8/gWvHDknPdoEQb4BbUMpMNqayw2BLi7yly?= =?iso-8859-1?Q?C+cWhgylSK0cahAHKp1T8041KzJbyloeRVmThftDHNvoVAWqfEmZiUh5SP?= =?iso-8859-1?Q?t2uBjMAVZyMKdGlnQBWg7jwisD16tKKAICkk7ftWto5J49HNelzbqkJXaA?= =?iso-8859-1?Q?2wQhDsNZM4agWi6RiH0UJUVKkmWFn2nvL87fvmCmIoB6wKlFA4XE2o37mf?= =?iso-8859-1?Q?/LYtVltY8ZY+Y+TmzaMtD5iP5GDIqKxqH9cB/7LSEwSGPphSzvo0hCIkDU?= =?iso-8859-1?Q?88jzvfAWQWXtyE4zHcesRk44TLItVrXUioI4Sn9cWdyIuD06GR9VF/+TNn?= =?iso-8859-1?Q?m4l8t0/XqlXfWUSLL9WUS3rQBKR/ZAJ2nCYUHUu1jGohTYqxIku/RKryb1?= =?iso-8859-1?Q?UZNM0h8B2dlHAEKRtfWiRTupYzW67fjEgoqYJ44/BhrSqOB8V4cFU3fk1B?= =?iso-8859-1?Q?4a9OOUKiAc9zBXLlQCFHyi5bSk4hWIUgmYt2nrW3U6xxzbPOKEFNX02Faq?= =?iso-8859-1?Q?d22s9pmvPB/eS8T4FS3ys5FwlbWLHu/hBCBQjMxXm1hYjGACjSiv+xO/RN?= =?iso-8859-1?Q?xtASM0G9jHHCxAihRU4ocVJ2byYPMGB09zU3/r3sgibUqB+2uiZcCZ5zyt?= =?iso-8859-1?Q?rxBRZEKJWz8YJ9Uo9TdsUi8H7o2oQO7Cb9POrWKngbHyQt3NxvxQ14h0U/?= =?iso-8859-1?Q?u16tOyXBD7vzNcbQ/cUKsT9pH7PMqJW49uXsxqcpLQRGM9dPlnimch4ma/?= =?iso-8859-1?Q?em/t+4GGbisWRAqigaoGUXqOQ3lCxOibw7SztPxLeZNymS5PEm5dJUmlpP?= =?iso-8859-1?Q?DrG6KkimIZq5tQsTEBb23oegsSumgIbSKXfDmkuG5OcgZTshehu2Pjn4b2?= =?iso-8859-1?Q?kcbYVX83uxPnKsGU+NL3rUeabjPvBug5zhGb/4LW/7SgtlWavioEacTByr?= =?iso-8859-1?Q?d4iXJlv+QLyuy5E7Rs65dXVPwCVGiDTN+ytNdlGka7zvFGKecc29MRv+Us?= =?iso-8859-1?Q?IuN2aNsE3lPCuM9sF7P/TJEFPjppez5yMBx7/sQuwQNiMC/lTHbX6A/A?= =?iso-8859-1?Q?=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: c0d36eee-dc91-4910-33d4-08de0d9da039 X-MS-Exchange-CrossTenant-AuthSource: DM4PR11MB6117.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Oct 2025 16:52:58.4805 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ahF6KRsQ1RVXcXa5Jup+VHgZFzcCUrmRSZpSq6ZNAFHR1ENawLYYH95elfI3elh3sqU+vzG6ceDOyoLnMTSCt/lhUklB/Bdim0BWKLCAruI= X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA4PR11MB8963 X-OriginatorOrg: intel.com On Fri, Oct 17, 2025 at 06:33:54PM +0200, Toke Høiland-Jørgensen wrote: > Maciej Fijalkowski writes: > > > Veth calls skb_pp_cow_data() which makes the underlying memory to > > originate from system page_pool. For CONFIG_DEBUG_VM=y and XDP program > > that uses bpf_xdp_adjust_tail(), following splat was observed: > > > > [ 32.204881] BUG: Bad page state in process test_progs pfn:11c98b > > [ 32.207167] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11c98b > > [ 32.210084] flags: 0x1fffe0000000000(node=0|zone=1|lastcpupid=0x7fff) > > [ 32.212493] raw: 01fffe0000000000 dead000000000040 ff11000123c9b000 0000000000000000 > > [ 32.218056] raw: 0000000000000000 0000000000000001 00000000ffffffff 0000000000000000 > > [ 32.220900] page dumped because: page_pool leak > > [ 32.222636] Modules linked in: bpf_testmod(O) bpf_preload > > [ 32.224632] CPU: 6 UID: 0 PID: 3612 Comm: test_progs Tainted: G O 6.17.0-rc5-gfec474d29325 #6969 PREEMPT > > [ 32.224638] Tainted: [O]=OOT_MODULE > > [ 32.224639] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > > [ 32.224641] Call Trace: > > [ 32.224644] > > [ 32.224646] dump_stack_lvl+0x4b/0x70 > > [ 32.224653] bad_page.cold+0xbd/0xe0 > > [ 32.224657] __free_frozen_pages+0x838/0x10b0 > > [ 32.224660] ? skb_pp_cow_data+0x782/0xc30 > > [ 32.224665] bpf_xdp_shrink_data+0x221/0x530 > > [ 32.224668] ? skb_pp_cow_data+0x6d1/0xc30 > > [ 32.224671] bpf_xdp_adjust_tail+0x598/0x810 > > [ 32.224673] ? xsk_destruct_skb+0x321/0x800 > > [ 32.224678] bpf_prog_004ac6bb21de57a7_xsk_xdp_adjust_tail+0x52/0xd6 > > [ 32.224681] veth_xdp_rcv_skb+0x45d/0x15a0 > > [ 32.224684] ? get_stack_info_noinstr+0x16/0xe0 > > [ 32.224688] ? veth_set_channels+0x920/0x920 > > [ 32.224691] ? get_stack_info+0x2f/0x80 > > [ 32.224693] ? unwind_next_frame+0x3af/0x1df0 > > [ 32.224697] veth_xdp_rcv.constprop.0+0x38a/0xbe0 > > [ 32.224700] ? common_startup_64+0x13e/0x148 > > [ 32.224703] ? veth_xdp_rcv_one+0xcd0/0xcd0 > > [ 32.224706] ? stack_trace_save+0x84/0xa0 > > [ 32.224709] ? stack_depot_save_flags+0x28/0x820 > > [ 32.224713] ? __resched_curr.constprop.0+0x332/0x3b0 > > [ 32.224716] ? timerqueue_add+0x217/0x320 > > [ 32.224719] veth_poll+0x115/0x5e0 > > [ 32.224722] ? veth_xdp_rcv.constprop.0+0xbe0/0xbe0 > > [ 32.224726] ? update_load_avg+0x1cb/0x12d0 > > [ 32.224730] ? update_cfs_group+0x121/0x2c0 > > [ 32.224733] __napi_poll+0xa0/0x420 > > [ 32.224736] net_rx_action+0x901/0xe90 > > [ 32.224740] ? run_backlog_napi+0x50/0x50 > > [ 32.224743] ? clockevents_program_event+0x1cc/0x280 > > [ 32.224746] ? hrtimer_interrupt+0x31e/0x7c0 > > [ 32.224749] handle_softirqs+0x151/0x430 > > [ 32.224752] do_softirq+0x3f/0x60 > > [ 32.224755] > > > > It's because xdp_rxq with mem model set to MEM_TYPE_PAGE_SHARED was used > > when initializing xdp_buff. > > > > Fix this by using new helper xdp_convert_skb_to_buff() that, besides > > init/prepare xdp_buff, will check if page used for linear part of > > xdp_buff comes from page_pool. We assume that linear data and frags will > > have same memory provider as currently XDP API does not provide us a way > > to distinguish it (the mem model is registered for *whole* Rx queue and > > here we speak about single buffer granularity). > > > > In order to meet expected skb layout by new helper, pull the mac header > > before conversion from skb to xdp_buff. > > > > However, that is not enough as before releasing xdp_buff out of veth via > > XDP_{TX,REDIRECT}, mem type on xdp_rxq associated with xdp_buff is > > restored to its original model. We need to respect previous setting at > > least until buff is converted to frame, as frame carries the mem_type. > > Add a page_pool variant of veth_xdp_get() so that we avoid refcount > > underflow when draining page frag. > > > > Fixes: 0ebab78cbcbf ("net: veth: add page_pool for page recycling") > > Reported-by: Alexei Starovoitov > > Closes: https://lore.kernel.org/bpf/CAADnVQ+bBofJDfieyOYzSmSujSfJwDTQhiz3aJw7hE+4E2_iPA@mail.gmail.com/ > > Signed-off-by: Maciej Fijalkowski > > --- > > drivers/net/veth.c | 43 +++++++++++++++++++++++++++---------------- > > 1 file changed, 27 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/net/veth.c b/drivers/net/veth.c > > index a3046142cb8e..eeeee7bba685 100644 > > --- a/drivers/net/veth.c > > +++ b/drivers/net/veth.c > > @@ -733,7 +733,7 @@ static void veth_xdp_rcv_bulk_skb(struct veth_rq *rq, void **frames, > > } > > } > > > > -static void veth_xdp_get(struct xdp_buff *xdp) > > +static void veth_xdp_get_shared(struct xdp_buff *xdp) > > { > > struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); > > int i; > > @@ -746,12 +746,33 @@ static void veth_xdp_get(struct xdp_buff *xdp) > > __skb_frag_ref(&sinfo->frags[i]); > > } > > > > +static void veth_xdp_get_pp(struct xdp_buff *xdp) > > +{ > > + struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); > > + int i; > > + > > + page_pool_ref_page(virt_to_page(xdp->data)); > > + if (likely(!xdp_buff_has_frags(xdp))) > > + return; > > + > > + for (i = 0; i < sinfo->nr_frags; i++) { > > + skb_frag_t *frag = &sinfo->frags[i]; > > + > > + page_pool_ref_page(netmem_to_page(frag->netmem)); > > + } > > +} > > + > > +static void veth_xdp_get(struct xdp_buff *xdp) > > +{ > > + xdp->rxq->mem.type == MEM_TYPE_PAGE_POOL ? > > + veth_xdp_get_pp(xdp) : veth_xdp_get_shared(xdp); > > +} > > + > > static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq, > > struct xdp_buff *xdp, > > struct sk_buff **pskb) > > { > > struct sk_buff *skb = *pskb; > > - u32 frame_sz; > > > > if (skb_shared(skb) || skb_head_is_locked(skb) || > > skb_shinfo(skb)->nr_frags || > > @@ -762,19 +783,9 @@ static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq, > > skb = *pskb; > > } > > > > - /* SKB "head" area always have tailroom for skb_shared_info */ > > - frame_sz = skb_end_pointer(skb) - skb->head; > > - frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); > > - xdp_init_buff(xdp, frame_sz, &rq->xdp_rxq); > > - xdp_prepare_buff(xdp, skb->head, skb_headroom(skb), > > - skb_headlen(skb), true); > > + __skb_pull(*pskb, skb->data - skb_mac_header(skb)); > > veth_xdp_rcv_skb() does: > > __skb_push(skb, skb->data - skb_mac_header(skb)); > if (veth_convert_skb_to_xdp_buff(rq, xdp, &skb)) > > so how about just getting rid of that push instead of doing the opposite > pull straight after? :) Hi Toke, I believe this is done so we get a proper headroom representation which is needed for XDP_PACKET_HEADROOM comparison. Maybe we could be smarter here and for example subtract mac header length? However I wanted to preserve old behavior. Thanks for review! Maciej > > -Toke >