Re: [GIT PULL] x86/mm changes for v5.9

[Jason A. Donenfeld]

Hi Ingo, Joerg,

On Mon, Aug 03, 2020 at 09:03:54PM +0200, Ingo Molnar wrote:
> Linus,
> 
> Please pull the latest x86/mm git tree from:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-mm-2020-08-03
> 
>    # HEAD: 2b32ab031e82a109e2c5b0d30ce563db0fe286b4 x86/mm/64: Make sync_global_pgds() static
> 
> The biggest change is to not sync the vmalloc and ioremap ranges for x86-64 anymore.
> 
>  Thanks,
> 
> 	Ingo
> 
> ------------------>
> Joerg Roedel (3):
>       x86/mm: Pre-allocate P4D/PUD pages for vmalloc area
>       x86/mm/64: Do not sync vmalloc/ioremap mappings
>       x86/mm/64: Make sync_global_pgds() static

The commit 8bb9bf242d1f ("x86/mm/64: Do not sync vmalloc/ioremap
mappings") causes the OOPS below, in Linus' tree and in linux-next,
unearthed by my CI on <https://www.wireguard.com/build-status/>.
Bisecting reveals 8bb9bf242d1f, and reverting this makes the OOPS go
away.

Jason


BUG: unable to handle page fault for address: ffffe8ffffd00608
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 2 PID: 22 Comm: kworker/2:0 Not tainted 5.8.0+ #154
RIP: 0010:process_one_work+0x2c/0x2d0
Code: 41 56 41 55 41 54 55 48 89 f5 53 48 89 fb 48 83 ec 08 48 8b 06 4c 8b 67 40 49 89 c6 45 30 f6 a8 04 b8 00 00 00 00 4c 0f 44 f0 <49> 8b 46 08 44 8b a8 00 01 05
RSP: 0018:ffff88800016be98 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888000010c00 RCX: 0000000000000000
RDX: 00000000fffedb85 RSI: ffff888000391900 RDI: ffff888000010c00
RBP: ffff888000391900 R08: ffff888000391900 R09: ffff888000350090
R10: ffffffffff770df6 R11: ffff88800f91f840 R12: ffff88800f91f140
R13: ffff88800f91f160 R14: ffffe8ffffd00600 R15: ffff88800f91f140
FS:  0000000000000000(0000) GS:ffff88800f900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffe8ffffd00608 CR3: 00000000001be005 CR4: 00000000001706a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 worker_thread+0x4b/0x3b0
 ? rescuer_thread+0x360/0x360
 kthread+0x116/0x140
 ? __kthread_create_worker+0x110/0x110
 ret_from_fork+0x1f/0x30
CR2: ffffe8ffffd00608
---[ end trace ca0cfc5a79414fb2 ]---
RIP: 0010:process_one_work+0x2c/0x2d0
Code: 41 56 41 55 41 54 55 48 89 f5 53 48 89 fb 48 83 ec 08 48 8b 06 4c 8b 67 40 49 89 c6 45 30 f6 a8 04 b8 00 00 00 00 4c 0f 44 f0 <49> 8b 46 08 44 8b a8 00 01 05
RSP: 0018:ffff88800016be98 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888000010c00 RCX: 0000000000000000
RDX: 00000000fffedb85 RSI: ffff888000391900 RDI: ffff888000010c00
RBP: ffff888000391900 R08: ffff888000391900 R09: ffff888000350090
R10: ffffffffff770df6 R11: ffff88800f91f840 R12: ffff88800f91f140
R13: ffff88800f91f160 R14: ffffe8ffffd00600 R15: ffff88800f91f140
FS:  0000000000000000(0000) GS:ffff88800f900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffe8ffffd00608 CR3: 00000000001be005 CR4: 00000000001706a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Kernel panic - not syncing: Fatal exception