Re: [PATCH v6] amba: Remove deferred device addition

[Guenter Roeck]

Hi,

On Wed, Jul 27, 2022 at 11:19:35AM -0700, Saravana Kannan wrote:
> The uevents generated for an amba device need PID and CID information
> that's available only when the amba device is powered on, clocked and
> out of reset. So, if those resources aren't available, the information
> can't be read to generate the uevents. To workaround this requirement,
> if the resources weren't available, the device addition was deferred and
> retried periodically.
> 
...

This patch results in a large number of crashes in various qemu
emulations. Crash and bisect logs below. Reverting this patch
fixes the problem.

Additional information: The decoded stack trace suggests that the
"id" parameter of pl011_probe() may be NULL.

Guenter

---
8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000008
[00000008] *pgd=00000000
Internal error: Oops: 5 [#1] ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0+ #1
Hardware name: ARM-Versatile (Device Tree Support)
PC is at pl011_probe+0x40/0x110
LR is at amba_probe+0x10c/0x19c
pc : [<c059847c>]    lr : [<c055ac9c>]    psr: 60000153
sp : c8811e00  ip : 00000000  fp : c1959ef8
r10: c7ef55f8  r9 : fffffdfb  r8 : c0d77af8
r7 : c1959c00  r6 : c1959c00  r5 : 00000000  r4 : 00000003
r3 : c14191a4  r2 : 00000dc0  r1 : 00000198  r0 : c1959c00
Flags: nZCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment none
Control: 00093177  Table: 00004000  DAC: 00000053
Register r0 information: slab kmalloc-1k start c1959c00 pointer offset 0 size 1024
Register r1 information: non-paged memory
Register r2 information: non-paged memory
Register r3 information: non-slab/vmalloc memory
Register r4 information: non-paged memory
Register r5 information: NULL pointer
Register r6 information: slab kmalloc-1k start c1959c00 pointer offset 0 size 1024
Register r7 information: slab kmalloc-1k start c1959c00 pointer offset 0 size 1024
Register r8 information: non-slab/vmalloc memory
Register r9 information: non-paged memory
Register r10 information: non-slab/vmalloc memory
Register r11 information: slab kmalloc-1k start c1959c00 pointer offset 760 size 1024
Register r12 information: NULL pointer
Process swapper (pid: 1, stack limit = 0x(ptrval))
Stack: (0xc8811e00 to 0xc8812000)
1e00: 60000153 00000009 c1959c00 00000000 c0d77af8 c055ac9c c055ab90 c1959c00
1e20: 00000000 c0d77af8 00000000 c1898d40 c180e158 c0cd8848 00000000 c05fbfe4
1e40: c1959c00 c0d77af8 c1959c00 00000000 c1898d40 c05fc250 c14195c4 60000153
1e60: c1959c00 c05fc2f8 c180e158 c0cd8848 00000000 00000000 c1959c00 c0d77af8
1e80: c0d72b98 c05fc704 00000000 c0d77af8 c05fc694 c0d72b98 c1898d40 c05fa0b4
1ea0: 00000000 c19458ac c1957eb4 c0cfb86c c0d77af8 c180e100 00000000 c05fb2ac
1ec0: c0bc2310 c0dad240 c1898d40 c0d77af8 c0dad240 c1898d40 00000000 c1898d40
1ee0: c0dbb000 c05fd258 c0cc55c4 c0dad240 c1898d40 c000a8b0 00000000 00000000
1f00: c18dbe47 c0c6cc00 00000137 c00488a8 c0c6b418 00000000 c0dad240 c0953980
1f20: c1898d40 00000003 c0dad240 c18dbe00 c0cd8864 c0c6b418 c0dbb000 c0cd8848
1f40: 00000000 c0cfb86c c0cf16a4 00000004 c18dbe00 c0cd8868 c0c6b418 c0ca5230
1f60: 00000003 00000003 00000000 c0ca4400 00000000 00000137 00000000 00000000
1f80: c0953c48 00000000 00000000 00000000 00000000 00000000 00000000 c0953c58
1fa0: 00000000 c0953c48 00000000 c00084f8 00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
 pl011_probe from amba_probe+0x10c/0x19c
 amba_probe from really_probe+0xb4/0x2a0
 really_probe from __driver_probe_device+0x80/0xe4
 __driver_probe_device from driver_probe_device+0x44/0x108
 driver_probe_device from __driver_attach+0x70/0x110
 __driver_attach from bus_for_each_dev+0x74/0xc0
 bus_for_each_dev from bus_add_driver+0x154/0x1e8
 bus_add_driver from driver_register+0x74/0x10c
 driver_register from do_one_initcall+0x8c/0x2fc
 do_one_initcall from kernel_init_freeable+0x190/0x220
 kernel_init_freeable from kernel_init+0x10/0x108
 kernel_init from ret_from_fork+0x14/0x3c
Exception stack(0xc8811fb0 to 0xc8811ff8)
1fa0:                                     00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
Code: e8bd81f0 e3a02d37 e3a01f66 e1a00007 (e59c8008)
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Reboot failed -- System halted
qemu-system-arm: terminating on signal 15 from pid 952897 (/bin/bash)

---
# bad: [c8a684e2e110376c58f0bfa30fb3855d1e319670] Merge tag 'leds-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds
# good: [3d7cb6b04c3f3115719235cc6866b10326de34cd] Linux 5.19
git bisect start 'HEAD' 'v5.19'
# good: [12b68040a5e468068fd7f4af1150eab8f6e96235] Merge tag 'media/v5.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
git bisect good 12b68040a5e468068fd7f4af1150eab8f6e96235
# bad: [5f0848190c6dd0f5b8a2aaf0f1d900a96d96bee0] Merge tag 'platform-drivers-x86-v6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86
git bisect bad 5f0848190c6dd0f5b8a2aaf0f1d900a96d96bee0
# good: [798cd57cd5f871452461746032cf6ee50b0fd69a] drm/amd/display: restore code for plane with no modifiers
git bisect good 798cd57cd5f871452461746032cf6ee50b0fd69a
# good: [723c188d5cd42a07344f997b0b7e1d83b4173c8d] Merge tag 'staging-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
git bisect good 723c188d5cd42a07344f997b0b7e1d83b4173c8d
# good: [a4850b5590d01bf3fb19fda3fc5d433f7382a974] Merge tag 'kvm-s390-next-5.20-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
git bisect good a4850b5590d01bf3fb19fda3fc5d433f7382a974
# bad: [8d9420ca9bd9bceddcfab3d0263d6a8e073396fe] Merge tag 'for-linus-2022080201' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid
git bisect bad 8d9420ca9bd9bceddcfab3d0263d6a8e073396fe
# good: [31f6e3832a0f1c366e54033335aed2375f6e447a] KVM: x86/mmu: remove unused variable
git bisect good 31f6e3832a0f1c366e54033335aed2375f6e447a
# good: [7df9075e232e09d99cf23b657b6cb04c9506e618] Merge tag 'csky-for-linus-6.0-rc1' of https://github.com/c-sky/csky-linux
git bisect good 7df9075e232e09d99cf23b657b6cb04c9506e618
# good: [c556717541c0c34bff887db92057964f0ff74582] Merge branch 'for-5.20/amd-sfh' into for-linus
git bisect good c556717541c0c34bff887db92057964f0ff74582
# good: [a60885b6a97b5dc9340dd9310a57b5682c2daf2d] Merge branch 'for-5.20/uclogic' into for-linus
git bisect good a60885b6a97b5dc9340dd9310a57b5682c2daf2d
# bad: [995177a4c75ee9b9069d5a313d90c005cf89c1b2] Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
git bisect bad 995177a4c75ee9b9069d5a313d90c005cf89c1b2
# good: [b97abb4d0e23766650619a6a57a52c91deb89b8a] ARM: 9217/1: add definition of arch_irq_work_raise()
git bisect good b97abb4d0e23766650619a6a57a52c91deb89b8a
# good: [fe520635ddc4377e84f78c6cf1c54393f1dfa33b] ARM: 9219/1: fix undeclared soft_restart
git bisect good fe520635ddc4377e84f78c6cf1c54393f1dfa33b
# bad: [f2d3b9a46e0ed4742abaa00506b18bb2ca9179d8] ARM: 9220/1: amba: Remove deferred device addition
git bisect bad f2d3b9a46e0ed4742abaa00506b18bb2ca9179d8
# first bad commit: [f2d3b9a46e0ed4742abaa00506b18bb2ca9179d8] ARM: 9220/1: amba: Remove deferred device addition