Re: linux-next 20191204: crash in mm/pagewalk.c

[Steven Price]

On Thu, Dec 05, 2019 at 12:23:02PM +0000, Valdis KlÄtnieks wrote:
> linux-next 20191204 dies a horrid death on my laptop while booting:

This is due to an unfortunate conflict between my series reworking of
the page walk infrastructure to reuse it for kernel walks and a commit
by Thomas Hellstrom to allow safe modification of entries in the
callback. See [1] for more detail.

I believe Andrew has dropped my series for now while I rework it to fix
this conflict.

Steve

[1] https://lore.kernel.org/linux-arm-kernel/20191204163235.GA1597@xxxxxxx/

> [   12.344975] Write protecting the kernel read-only data: 26624k
> [   12.348497] Freeing unused kernel image (text/rodata gap) memory: 2036K
> [   12.349701] Freeing unused kernel image (rodata/data gap) memory: 1056K
> [   12.349756] BUG: kernel NULL pointer dereference, address: 0000000000000018
> [   12.349810] #PF: supervisor read access in kernel mode
> [   12.349904] #PF: error_code(0x0000) - not-present page
> [   12.349920] PGD 0 P4D 0
> [   12.349996] Oops: 0000 [#1] SMP
> [   12.350012] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G                T 5.4.0-next-20191204-dirty #703
> [   12.350031] Hardware name: TOSHIBA Satellite C55-B/ZBWAA, BIOS 5.00 07/23/2015
> [   12.350055] RIP: 0010:__lock_acquire+0x465/0x810
> [   12.350132] Code: 00 85 c0 74 10 44 8b 25 79 17 ba 01 45 85 e4 0f 84 c4 30 00 00 45 31 e4 48 83 c4 30 44 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <49> 81 3e 60 32 0c 9d 41 ba 00 00 00 00 45 0f 45 d7 41 83 fc 01 0f
> [   12.350163] RSP: 0018:ffffb2f940053b70 EFLAGS: 00010002
> [   12.350179] RAX: ffff8896c7d74040 RBX: 0000000000000000 RCX: 0000000000000000
> [   12.350195] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000018
> [   12.350211] RBP: ffffb2f940053bc8 R08: 0000000000000001 R09: 0000000000000000
> [   12.350227] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
> [   12.350305] R13: 0000000000000000 R14: 0000000000000018 R15: 0000000000000001
> [   12.350323] FS:  0000000000000000(0000) GS:ffff8897f7a00000(0000) knlGS:0000000000000000
> [   12.350340] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   12.350355] CR2: 0000000000000018 CR3: 0000000028a24000 CR4: 00000000001006f0
> [   12.350370] Call Trace:
> [   12.350385]  ? __bfs+0x2c/0x300
> [   12.350404]  lock_acquire+0x90/0x170
> [   12.350421]  ? walk_pgd_range+0x556/0x7b0
> [   12.350441]  _raw_spin_lock+0x31/0x70
> [   12.350463]  ? walk_pgd_range+0x556/0x7b0
> [   12.350479]  walk_pgd_range+0x556/0x7b0
> [   12.350500]  __walk_page_range+0x1a5/0x1c0
> [   12.350517]  ? __lock_acquired+0x1f8/0x310
> [   12.350534]  walk_page_range_novma+0x72/0xc0
> [   12.350553]  ptdump_walk_pgd+0x47/0x80
> [   12.350570]  ptdump_walk_pgd_level_core+0xc3/0xf0
> [   12.350588]  ? ptdump_walk_pgd_level_debugfs+0x30/0x30
> [   12.350683]  ? 0xffffffff9b000000
> [   12.350699]  ptdump_walk_pgd_level_checkwx+0x19/0x1b
> [   12.350717]  mark_rodata_ro+0xc2/0xc9
> [   12.350732]  ? rest_init+0x2c1/0x2eb
> [   12.350747]  kernel_init+0x3d/0x105
> [   12.350761]  ? rest_init+0x2eb/0x2eb
> [   12.350783]  ret_from_fork+0x3a/0x50
> [   12.350797] Modules linked in:
> [   12.350810] CR2: 0000000000000018
> [   12.350822] ---[ end trace 5060898a61f6b985 ]---
> [   12.424261] probe of 1-1 returned 1 after 1829 usecs
> [   12.453678] calling  sdhci_drv_init+0x0/0x4a @ 1
> [   12.527751] RIP: 0010:__lock_acquire+0x465/0x810
> [   12.527771] Code: 00 85 c0 74 10 44 8b 25 79 17 ba 01 45 85 e4 0f 84 c4 30 00 00 45 31 e4 48 83 c4 30 44 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <49> 81 3e 60 32 0c 9d 41 ba 00 00 00 00 45 0f 45 d7 41 83 fc 01 0f
> [   12.527792] RSP: 0018:ffffb2f940053b70 EFLAGS: 00010002
> [   12.527803] RAX: ffff8896c7d74040 RBX: 0000000000000000 RCX: 0000000000000000
> [   12.527814] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000018
> [   12.527825] RBP: ffffb2f940053bc8 R08: 0000000000000001 R09: 0000000000000000
> [   12.527836] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
> [   12.527846] R13: 0000000000000000 R14: 0000000000000018 R15: 0000000000000001
> [   12.527858] FS:  0000000000000000(0000) GS:ffff8897f7a00000(0000) knlGS:0000000000000000
> [   12.527879] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   12.527894] CR2: 0000000000000018 CR3: 000000023060a000 CR4: 00000000001006f0
> [   12.527911] Kernel panic - not syncing: Fatal exception
>