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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Kn51Zo3e0jpjC53+LjxSPZmrV2SIGQoCmIbh7HK4iwYYVK92z4nLjP4V4tbn?= =?us-ascii?Q?2UE0wLJOC/plNNzrAegpsDKuKTfp+xu1aRYdDhzbQZnVT4C5OzUy8+6Sx1/Z?= =?us-ascii?Q?qaCLFx7785WjwapJCeF97mIASirZBfJN29p6l7ds0NBLsi/amhbiIAxUUHtU?= =?us-ascii?Q?iC7tR7k7WDtFtJGGgN9dxz1F5cY9P8nTFeP8spLrpbNl5xmiEeqRBWX4w2tD?= =?us-ascii?Q?guqgED/mVYUHcEXV41lux+vVgTuaTDV81Fv/vsO6AQ3RrHDxD7Z168HQESx2?= =?us-ascii?Q?qrVc3Qz6gvf97pqwwLyvhHiWN5M4RqPsHrUuwEp1AdY8DeVmsMyRlEdCCCZJ?= =?us-ascii?Q?lBEL+0W5DX++43+rUZ5H++CHAlO4qQzSXFY0GE09zR2IUtBXr8gir/3SPe8t?= =?us-ascii?Q?p0bdShBn/ryAxyJOm3eaCEGVsG2CyK0ZIfQofI3kNLd4USfvNqxmA/UfOx7I?= =?us-ascii?Q?2LKHt5jhu9JYDsubVk14wAm8KUP52JFC2VIrmWsuou2rusn4/m7+9ag6uqcG?= =?us-ascii?Q?v9phV7FwyPDbWLCncPFlYSSJUGjxwOxlGWH+Do728/iZSQpCZPeQJEnSEZzQ?= =?us-ascii?Q?G0nvcawiRIJ6YngL20wLELDIzXh4cDQqwKmfSqbqjADKg7cMoHaXyMozbVRa?= =?us-ascii?Q?ew4fO6kRw4vMNrcGmYpQdZU2HPyoKIuKix+lVjAsCiiJIj6cpj3NRVQUpCaa?= =?us-ascii?Q?DDFW2A3OOKLEBtHAghzDU3ZWZHJZE3U+VRWvraSCgjhN8Hf7ebN3LDdccTAy?= =?us-ascii?Q?hN9IBlJtsWa+FG0R+LoQgbifDe7GqTxeP295ZeM8BrqzEyDj4hy1aPaRB04v?= =?us-ascii?Q?SH9tds3gSKV+k/yvWnmT+oDDXWfZ0XNJj20nmVw+cEyvzgQxQvat/gpMRpNC?= =?us-ascii?Q?YJ1d/3Cx3qOsQBq3X/P1SUdiRBG3cT2by/LrKE5tNWOlrDFP0/LNccXRyJLb?= =?us-ascii?Q?zU9X9mxTQYcGE4vtc/D2spotAQd2ILYaeqU0FHz8K7HmFh+iBpl3hMO9lg4O?= =?us-ascii?Q?CDjUx0qHc8BLRXDARU3aFdHAtGHfpT6DFOLMMDI+qLRaQ58N1QassuXmfjtT?= =?us-ascii?Q?KAtWM7yAznfNPPI9zVz8Ec//HhcbjsKqSUjU5StjIDf5mupqil16BQ2hKgsP?= =?us-ascii?Q?IKhD/Trw8TV0qpKyjW7/FKOaem/p5OrlRWadXCY+V81R3qAbMSoUAI+o1VkS?= =?us-ascii?Q?/GYj9NTIgMiRTpsMAncQ2fybZyTYxrSeIhT9BQNj5D4YaLrVtftUn46WFVmV?= =?us-ascii?Q?A0Q5TxxcAFTZou+f8xC/tRcmuiEOxEF2BogTvL8hXwNlZDvBUlmXFEafdPob?= =?us-ascii?Q?2AbMmz1893fqdxQaGDwXV8S41+VsiiYZMuwjDBuqwrfaSSD49g+QiSe+dzwF?= =?us-ascii?Q?89vCe7qiepgcPCGnKfMnXXN+p4NaSF6GziGwfztlc8y4Z0nKpk1CmbvMdnjk?= =?us-ascii?Q?nRsjoIJqCHxJ7BSXn3NW6MLMnNjKLPrXSeU5mey5Oe8QECPPtjmwaAP2fdHg?= =?us-ascii?Q?OvDV/M3JZXyU6VjRzR+nZuZOBPJFemW+MOgYq4YntMpa5tHwA851FOHx6TQg?= =?us-ascii?Q?gr9wea91sZ5ljgLcwihBdg5JUMBBwGWDumTS5+XE2MDVoRK6Dvb8KjgxFaLn?= =?us-ascii?Q?0HK5i4CahUbqkFSvvpiB66weFZw8JEWSbN2IOt+LVs5fPNtGxmBWDe/m3oA0?= =?us-ascii?Q?u6IuWw=3D=3D?= X-OriginatorOrg: corigine.com X-MS-Exchange-CrossTenant-Network-Message-Id: 10855402-06f5-4f91-1bee-08db52fed546 X-MS-Exchange-CrossTenant-AuthSource: PH0PR13MB4842.namprd13.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 May 2023 15:37:46.0477 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: fe128f2c-073b-4c20-818e-7246a585940c X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 2kDIQ09R5jU01+Gk+Dc/KKlOFYaE2S5QhR1eDzg7PJWLQygmBA6S2tDj0v8RSPfM4TB6v+vS9m2Qjf5i3nCyyeddn2SBlEWD0z1qojR4ipY= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR13MB5503 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Fri, May 12, 2023 at 03:23:30PM +0200, Maciej Fijalkowski wrote: > The ice driver caches next_to_clean value at the beginning of > ice_clean_rx_irq() in order to remember the first buffer that has to be > freed/recycled after main Rx processing loop. The end is indicated by > first descriptor of packet that the Rx processing loop has ended. Note > that if mentioned loop ended in the middle of gathering a multi-buffer > packet, next_to_clean would be pointing to the descriptor in the middle > of the packet BUT freeing/recycling stage will stop at the first > descriptor. This means that next iteration of ice_clean_rx_irq() will > miss the (first_desc, next_to_clean - 1) entries. > > When running various 9K MTU workloads, such splats were observed, > mostly related to rx_buf->page being NULL as behavior described in the > paragraph above breaks ICE_RX_DESC_UNUSED() macro which is used when > refilling Rx buffers: > > [ 540.780716] BUG: kernel NULL pointer dereference, address: 0000000000000000 > [ 540.787787] #PF: supervisor read access in kernel mode > [ 540.793002] #PF: error_code(0x0000) - not-present page > [ 540.798218] PGD 0 P4D 0 > [ 540.800801] Oops: 0000 [#1] PREEMPT SMP NOPTI > [ 540.805231] CPU: 18 PID: 3984 Comm: xskxceiver Tainted: G W 6.3.0-rc7+ #96 > [ 540.813619] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 > [ 540.824209] RIP: 0010:ice_clean_rx_irq+0x2b6/0xf00 [ice] > [ 540.829678] Code: 74 24 10 e9 aa 00 00 00 8b 55 78 41 31 57 10 41 09 c4 4d 85 ff 0f 84 83 00 00 00 49 8b 57 08 41 8b 4f 1c 65 8b 35 1a fa 4b 3f <48> 8b 02 48 c1 e8 3a 39 c6 0f 85 a2 00 00 00 f6 42 08 02 0f 85 98 > [ 540.848717] RSP: 0018:ffffc9000f42fc50 EFLAGS: 00010282 > [ 540.854029] RAX: 0000000000000004 RBX: 0000000000000002 RCX: 000000000000fffe > [ 540.861272] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000ffffffff > [ 540.868519] RBP: ffff88984a05ac00 R08: 0000000000000000 R09: dead000000000100 > [ 540.875760] R10: ffff88983fffcd00 R11: 000000000010f2b8 R12: 0000000000000004 > [ 540.883008] R13: 0000000000000003 R14: 0000000000000800 R15: ffff889847a10040 > [ 540.890253] FS: 00007f6ddf7fe640(0000) GS:ffff88afdf800000(0000) knlGS:0000000000000000 > [ 540.898465] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 540.904299] CR2: 0000000000000000 CR3: 000000010d3da001 CR4: 00000000007706e0 > [ 540.911542] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 540.918789] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 540.926032] PKRU: 55555554 > [ 540.928790] Call Trace: > [ 540.931276] > [ 540.933418] ice_napi_poll+0x4ca/0x6d0 [ice] > [ 540.937804] ? __pfx_ice_napi_poll+0x10/0x10 [ice] > [ 540.942716] napi_busy_loop+0xd7/0x320 > [ 540.946537] xsk_recvmsg+0x143/0x170 > [ 540.950178] sock_recvmsg+0x99/0xa0 > [ 540.953729] __sys_recvfrom+0xa8/0x120 > [ 540.957543] ? do_futex+0xbd/0x1d0 > [ 540.961008] ? __x64_sys_futex+0x73/0x1d0 > [ 540.965083] __x64_sys_recvfrom+0x20/0x30 > [ 540.969155] do_syscall_64+0x38/0x90 > [ 540.972796] entry_SYSCALL_64_after_hwframe+0x72/0xdc > [ 540.977934] RIP: 0033:0x7f6de5f27934 > > To fix this, compare next_to_clean with first_desc at the beginning of > ice_clean_rx_irq(). In the case they are not the same, set cached_ntc to > first_desc so that at the end, when freeing/recycling buffers, > descriptors from first to ntc are not missed. > > Fixes: 2fba7dc5157b ("ice: Add support for XDP multi-buffer on Rx side") > Signed-off-by: Maciej Fijalkowski > --- > drivers/net/ethernet/intel/ice/ice_txrx.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c > index 4fcf2d07eb85..4d1fc047767f 100644 > --- a/drivers/net/ethernet/intel/ice/ice_txrx.c > +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c > @@ -1162,6 +1162,9 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget) > bool failure; > u32 first; > > + if (ntc != rx_ring->first_desc) > + cached_ntc = rx_ring->first_desc; > + Above ntc is initialised as rx_ring->next_to_clean. And cached_ntc is initialised as ntc, i.e. rx_ring->next_to_clean. u32 ntc = rx_ring->next_to_clean; ... u32 cached_ntc = ntc; So in effect we have: if (rx_ring->next_to_clean != rx_ring->first_desc) cached_ntc = rx_ring->first_desc; else cached_ntc = rx_ring->next_to_clean; I wonder if we can simplify this by simply initialising cached_ntc as: cached_ntc = rx_ring->first_desc;