Xen NIC driver have page_pool memory leaks

[Jesper Dangaard Brouer <hawk@kernel.org>]

Hi Arthur,

(Answer inlined below, which is custom on this mailing list)

On 23/03/2024 14.23, Arthur Borsboom wrote:
> Hi Jesper,
> 
> After a recent kernel upgrade 6.7.6 > 6.8.1 all my Xen guests on Arch
> Linux are dumping kernel traces.
> It seems to be indirectly caused by the page pool memory leak
> mechanism, which is probably a good thing.
> 
> I have created a bug report, but there is no response.
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=218618
> 
> I am uncertain where and to whom I need to report this page leak.
> Can you help me get this issue fixed?

I'm the page_pool maintainer, but as you say yourself in comment 2 then
since dba1b8a7ab68 ("mm/page_pool: catch page_pool memory leaks") this
indicated there is a problem in the xen_netfront driver, which was
previously not visible.

Cc'ing the "XEN NETWORK BACKEND DRIVER" maintainers, as this is a driver
bug.  What confuses me it that I cannot find any modules named
"xen_netfront" in the upstream tree.

IPSEC recently had a similar leak bug. That was fixed in commmit [1]
c3198822c6cb ("net: esp: fix bad handling of pages from page_pool").
This xen_netfront driver likely needs a similar fix.

--Jesper

[1] https://git.kernel.org/torvalds/c/c3198822c6cb


Text copied from bugzilla.kernel.org:
-------------------------------------
[88847.284348] Call Trace:
[88847.284354]  <IRQ>
[88847.284361]  dump_stack_lvl+0x47/0x60
[88847.284378]  bad_page+0x71/0x100
[88847.284393]  free_unref_page_prepare+0x236/0x390
[88847.284405]  free_unref_page+0x34/0x180
[88847.284416]  __pskb_pull_tail+0x3ff/0x4a0
[88847.284432]  xennet_poll+0x909/0xa40 [xen_netfront 
12c02fdcf84c692965d9cd6ca5a6ff0a530b4ce9]
[88847.284470]  __napi_poll+0x28/0x1b0
[88847.284483]  net_rx_action+0x2b5/0x370
[88847.284495]  ? handle_irq_desc+0x3e/0x60
[88847.284511]  __do_softirq+0xc9/0x2c8
[88847.284523]  __irq_exit_rcu+0xa3/0xc0
[88847.284536]  sysvec_xen_hvm_callback+0x72/0x90
[88847.284545]  </IRQ>
[88847.284549]  <TASK>
[88847.284552]  asm_sysvec_xen_hvm_callback+0x1a/0x20
[88847.284562] RIP: 0010:pv_native_safe_halt+0xf/0x20
[88847.284572] Code: 22 d7 c3 cc cc cc cc 0f 1f 40 00 90 90 90 90 90 90 
90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 13 27 00 fb 
f4 <c3> cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90
[88847.284579] RSP: 0018:ffffb2a1800c3e58 EFLAGS: 00000246
[88847.284587] RAX: 0000000000004000 RBX: ffff91358033b864 RCX: 
000051404aebd79d
[88847.284594] RDX: ffff9136f9b00000 RSI: ffff91358033b800 RDI: 
0000000000000001
[88847.284599] RBP: ffff91358033b864 R08: ffffffff9b94dca0 R09: 
0000000000000001
[88847.284604] R10: 0000000000000018 R11: ffff9136f9b331a4 R12: 
ffffffff9b94dca0
[88847.284609] R13: ffffffff9b94dd20 R14: 0000000000000001 R15: 
0000000000000000
[88847.284623]  acpi_safe_halt+0x15/0x30
[88847.284634]  acpi_idle_do_entry+0x2f/0x50
[88847.284644]  acpi_idle_enter+0x7f/0xd0
[88847.284655]  cpuidle_enter_state+0x81/0x440
[88847.284667]  cpuidle_enter+0x2d/0x40
[88847.284678]  do_idle+0x1d8/0x230
[88847.284688]  cpu_startup_entry+0x2a/0x30
[88847.284695]  start_secondary+0x11e/0x140
[88847.284705]  secondary_startup_64_no_verify+0x184/0x18b
[88847.284725]  </TASK>