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Message-ID: <aNqZsZAbqNieTkjS@boxer> Date: Mon, 29 Sep 2025 16:37:37 +0200 From: Maciej Fijalkowski <maciej.fijalkowski@...el.com> To: Bastien Curutchet <bastien.curutchet@...tlin.com> CC: Alexei Starovoitov <alexei.starovoitov@...il.com>, Björn Töpel <bjorn@...nel.org>, Magnus Karlsson <magnus.karlsson@...el.com>, Jonathan Lemon <jonathan.lemon@...il.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, "Yonghong Song" <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, "KP Singh" <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, "Jesper Dangaard Brouer" <hawk@...nel.org>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Alexis Lothore <alexis.lothore@...tlin.com>, Network Development <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>, "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH bpf-next v4 04/15] selftests/bpf: test_xsk: fix memory leak in testapp_stats_rx_dropped() On Mon, Sep 29, 2025 at 10:57:45AM +0200, Bastien Curutchet wrote: > On 9/27/25 1:19 PM, Alexei Starovoitov wrote: > > On Fri, Sep 26, 2025 at 12:47 PM Maciej Fijalkowski > > <maciej.fijalkowski@...el.com> wrote: > > > > > > On Fri, Sep 26, 2025 at 08:39:28AM +0200, Bastien Curutchet wrote: > > > > Hi Maciej, > > > > > > > > On 9/25/25 3:32 PM, Maciej Fijalkowski wrote: > > > > > On Wed, Sep 24, 2025 at 04:49:39PM +0200, Bastien Curutchet (eBPF Foundation) wrote: > > > > > > testapp_stats_rx_dropped() generates pkt_stream twice. The last > > > > > > generated is released by pkt_stream_restore_default() at the end of the > > > > > > test but we lose the pointer of the first pkt_stream. > > > > > > > > > > > > Release the 'middle' pkt_stream when it's getting replaced to prevent > > > > > > memory leaks. > > > > > > > > > > > > Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@...tlin.com> > > > > > > --- > > > > > > tools/testing/selftests/bpf/test_xsk.c | 7 +++++++ > > > > > > 1 file changed, 7 insertions(+) > > > > > > > > > > > > diff --git a/tools/testing/selftests/bpf/test_xsk.c b/tools/testing/selftests/bpf/test_xsk.c > > > > > > index 8d7c38eb32ca3537cb019f120c3350ebd9f8c6bc..eb18288ea1e4aa1c9337d16333b7174ecaed0999 100644 > > > > > > --- a/tools/testing/selftests/bpf/test_xsk.c > > > > > > +++ b/tools/testing/selftests/bpf/test_xsk.c > > > > > > @@ -536,6 +536,13 @@ static void pkt_stream_receive_half(struct test_spec *test) > > > > > > struct pkt_stream *pkt_stream = test->ifobj_tx->xsk->pkt_stream; > > > > > > u32 i; > > > > > > + if (test->ifobj_rx->xsk->pkt_stream != test->rx_pkt_stream_default) > > > > > > + /* Packet stream has already been replaced so we have to release this one. > > > > > > + * The newly created one will be freed by the restore_default() at the > > > > > > + * end of the test > > > > > > + */ > > > > > > + pkt_stream_delete(test->ifobj_rx->xsk->pkt_stream); > > > > > > > > > > I don't see why this one is not addressed within test case > > > > > (testapp_stats_rx_dropped()) and other fix is (testapp_xdp_shared_umem()). > > > > > > > > > > > > > pkt_stream_receive_half() can be used by other tests. I thought it would be > > > > > > So is pkt_stream_replace_half() and other routines that eventually call > > > pkt_stream_generate() and overwrite the pkt_stream, right? > > > > > > It just feels odd to have a special treatment in one function and other > > > are left as-is just because currently we don't have another abusive test > > > case. > > > > > > Maybe it's enough of bike-shedding here, just wanted to clarify on my POV. > > > > > > In the end don't get me wrong here, this interface is a bit PITA for me > > > and thanks for whole effort! > > > > My reading of this discussion that it doesn't block the series > > and can be done in the follow up if necessary. > > > > So I was planning to apply it, but it found real bugs: > > > > ./test_progs -t xsk > > [ 18.066989] bpf_testmod: loading out-of-tree module taints kernel. > > [ 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] <IRQ> > > [ 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] </IRQ> > > [ 32.224756] <TASK> > > [ 32.224757] __local_bh_enable_ip+0x58/0x60 > > [ 32.224759] __dev_direct_xmit+0x295/0x540 > > [ 32.224762] __xsk_generic_xmit+0x180a/0x2df0 > > [ 32.224764] ? ___kmalloc_large_node+0xdf/0x130 > > [ 32.224767] ? __mutex_unlock_slowpath.isra.0+0x330/0x330 > > [ 32.224770] ? __rtnl_unlock+0x65/0xd0 > > [ 32.224773] ? xsk_create+0x700/0x700 > > [ 32.224774] ? netdev_run_todo+0xce/0xbe0 > > [ 32.224777] ? _raw_spin_lock_irqsave+0x7b/0xc0 > > [ 32.224780] xsk_sendmsg+0x365/0x770 > > [ 32.224782] ? xsk_poll+0x640/0x640 > > [ 32.224783] __sock_sendmsg+0xc1/0x150 > > [ 32.224787] __sys_sendto+0x1d0/0x260 > > [ 32.224790] ? __ia32_sys_getpeername+0xb0/0xb0 > > [ 32.224793] ? fput+0x29/0x80 > > [ 32.224796] ? __sys_bind+0x187/0x1c0 > > [ 32.224798] ? __sys_bind_socket+0x90/0x90 > > [ 32.224801] ? randomize_page+0x60/0x60 > > [ 32.224804] ? fget+0x18e/0x230 > > [ 32.224807] __x64_sys_sendto+0xe0/0x1b0 > > [ 32.224810] ? fpregs_assert_state_consistent+0x57/0xe0 > > [ 32.224812] do_syscall_64+0x46/0x180 > > [ 32.224815] entry_SYSCALL_64_after_hwframe+0x4b/0x53 > > > > and at the end: > > > > # ERROR: [receive_pkts] Receive loop timed out > > test_xsk:FAIL:Run test unexpected error: -1 (errno 12) > > #251/32 ns_xsk_drv/XDP_ADJUST_TAIL_SHRINK_MULTI_BUFF:FAIL > > #251 ns_xsk_drv:FAIL > > Summary: 1/67 PASSED, 0 SKIPPED, 1 FAILED > > > > [ 99.308243] page_pool_release_retry() stalled pool shutdown: id > > 185, 48 inflight 60 sec > > [ 159.724173] page_pool_release_retry() stalled pool shutdown: id > > 185, 48 inflight 120 sec > > > > > > The test is great and the work to make it run as part of test_progs > > paid off big time. > > > > But we cannot enable it by default, since it will be crashing CI VMs. > > > > Please reproduce the above issue. > > You might need > > CONFIG_DEBUG_VM=y > > and other mm debug flags. > > > > I did reproduce the issue with CONFIG_DEBUG_VM=y > > > If the fix can be done quickly let's land the fix first. > > If not, please respin the series, but disable the test by default > > until the bug is fixed. > > I won't have much time this week to investigate this further, so I'll respin > the series with this test in the 'flaky table'. I'll take a look at the splat then. > > Best regards, > -- > Bastien Curutchet, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com >
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