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The mlxbf_gige driver encounters a NULL pointer exception in
mlxbf_gige_open() when kdump is enabled. The sequence to reproduce
the exception is as follows:
a) enable kdump
b) trigger kdump via "echo c > /proc/sysrq-trigger"
c) kdump kernel executes
d) kdump kernel loads mlxbf_gige module
e) the mlxbf_gige module runs its open() as the
the "oob_net0" interface is brought up
f) mlxbf_gige module will experience an exception
during its open(), something like:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x0000000086000004
EC = 0x21: IABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=00000000e29a4000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000086000004 [#1] SMP
CPU: 0 PID: 812 Comm: NetworkManager Tainted: G OE 5.15.0-1035-bluefield #37-Ubuntu
Hardware name: https://www.mellanox.com BlueField-3 SmartNIC Main Card/BlueField-3 SmartNIC Main Card, BIOS 4.6.0.13024 Jan 19 2024
pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : 0x0
lr : __napi_poll+0x40/0x230
sp : ffff800008003e00
x29: ffff800008003e00 x28: 0000000000000000 x27: 00000000ffffffff
x26: ffff000066027238 x25: ffff00007cedec00 x24: ffff800008003ec8
x23: 000000000000012c x22: ffff800008003eb7 x21: 0000000000000000
x20: 0000000000000001 x19: ffff000066027238 x18: 0000000000000000
x17: ffff578fcb450000 x16: ffffa870b083c7c0 x15: 0000aaab010441d0
x14: 0000000000000001 x13: 00726f7272655f65 x12: 6769675f6662786c
x11: 0000000000000000 x10: 0000000000000000 x9 : ffffa870b0842398
x8 : 0000000000000004 x7 : fe5a48b9069706ea x6 : 17fdb11fc84ae0d2
x5 : d94a82549d594f35 x4 : 0000000000000000 x3 : 0000000000400100
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000066027238
Call trace:
0x0
net_rx_action+0x178/0x360
__do_softirq+0x15c/0x428
__irq_exit_rcu+0xac/0xec
irq_exit+0x18/0x2c
handle_domain_irq+0x6c/0xa0
gic_handle_irq+0xec/0x1b0
call_on_irq_stack+0x20/0x2c
do_interrupt_handler+0x5c/0x70
el1_interrupt+0x30/0x50
el1h_64_irq_handler+0x18/0x2c
el1h_64_irq+0x7c/0x80
__setup_irq+0x4c0/0x950
request_threaded_irq+0xf4/0x1bc
mlxbf_gige_request_irqs+0x68/0x110 [mlxbf_gige]
mlxbf_gige_open+0x5c/0x170 [mlxbf_gige]
__dev_open+0x100/0x220
__dev_change_flags+0x16c/0x1f0
dev_change_flags+0x2c/0x70
do_setlink+0x220/0xa40
__rtnl_newlink+0x56c/0x8a0
rtnl_newlink+0x58/0x84
rtnetlink_rcv_msg+0x138/0x3c4
netlink_rcv_skb+0x64/0x130
rtnetlink_rcv+0x20/0x30
netlink_unicast+0x2ec/0x360
netlink_sendmsg+0x278/0x490
__sock_sendmsg+0x5c/0x6c
____sys_sendmsg+0x290/0x2d4
___sys_sendmsg+0x84/0xd0
__sys_sendmsg+0x70/0xd0
__arm64_sys_sendmsg+0x2c/0x40
invoke_syscall+0x78/0x100
el0_svc_common.constprop.0+0x54/0x184
do_el0_svc+0x30/0xac
el0_svc+0x48/0x160
el0t_64_sync_handler+0xa4/0x12c
el0t_64_sync+0x1a4/0x1a8
Code: bad PC value
---[ end trace 7d1c3f3bf9d81885 ]---
Kernel panic - not syncing: Oops: Fatal exception in interrupt
Kernel Offset: 0x2870a7a00000 from 0xffff800008000000
PHYS_OFFSET: 0x80000000
CPU features: 0x0,000005c1,a3332a5a
Memory Limit: none
---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---
The exception happens because there is a pending RX interrupt before the
call to request_irq(RX IRQ) executes. Then, the RX IRQ handler fires
immediately after this request_irq() completes. The RX IRQ handler runs
"napi_schedule()" before NAPI is fully initialized via "netif_napi_add()"
and "napi_enable()", both which happen later in the open() logic.
The logic in mlxbf_gige_open() must fully initialize NAPI before any calls
to request_irq() execute.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.