Re: scheduler problems in -next (was: Re: [PATCH 6.4 000/227] 6.4.7-rc1 review)

[Peter Zijlstra]

On Mon, Jul 31, 2023 at 07:35:13AM -0700, Guenter Roeck wrote:

> > Hurmph, let me see if I can reproduce on next-20230731 (not having the
> > older next thingies around).
> 
> That crashes hard with my configuration.
> 
> [    6.353191] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
> [    6.353392] BUG: unable to handle page fault for address: ffff9b10c0013cd0
> [    6.353531] #PF: supervisor instruction fetch in kernel mode
> [    6.353624] #PF: error_code(0x0011) - permissions violation
> [    6.353751] PGD 1000067 P4D 1000067 PUD 1205067 PMD 1206067 PTE 800000000124e063
> [    6.354011] Oops: 0011 [#1] PREEMPT SMP PTI
> [    6.354164] CPU: 0 PID: 182 Comm: kunit_try_catch Tainted: G                 N 6.5.0-rc4-next-20230731 #1
> [    6.354315] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
> [    6.354525] RIP: 0010:0xffff9b10c0013cd0
> [    6.354793] Code: ff ff 60 64 ce a9 ff ff ff ff 00 00 00 00 00 00 00 00 d1 3a bc a8 ff ff ff ff 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <f0> 00 01 44 10 8a ff ff b8 01 01 44 10 8a ff ff 00 00 00 00 00 00
> [    6.355059] RSP: 0000:ffff9b10c027fd60 EFLAGS: 00000246
> [    6.355157] RAX: ffff9b10c0013cd0 RBX: ffff8a1043bdb400 RCX: 0000000000000000
> [    6.355259] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8a1043bdb400
> [    6.355358] RBP: ffff9b10c027fdc8 R08: 0000000000000001 R09: 0000000000000001
> [    6.355456] R10: 0000000000000001 R11: 0000000000000001 R12: ffff9b10c027fe74
> [    6.355556] R13: ffff8a10440100f0 R14: ffff8a10440101b8 R15: ffff9b10c027fe74
> [    6.355679] FS:  0000000000000000(0000) GS:ffff8a104fc00000(0000) knlGS:0000000000000000
> [    6.355798] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    6.355886] CR2: ffff9b10c0013cd0 CR3: 000000000e048000 CR4: 00000000003506f0
> [    6.356029] Call Trace:
> [    6.356158]  <TASK>
> [    6.356334]  ? __die+0x1f/0x70
> [    6.356472]  ? page_fault_oops+0x14a/0x460
> [    6.356547]  ? exc_page_fault+0xee/0x1c0
> [    6.356612]  ? asm_exc_page_fault+0x26/0x30
> [    6.356703]  ? kunit_filter_attr_tests+0xc4/0x2e0
> [    6.356796]  kunit_filter_suites+0x2e2/0x460
> [    6.356889]  ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
> [    6.356979]  filter_suites_test+0xea/0x2c0
> [    6.357051]  ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
> [    6.357148]  kunit_generic_run_threadfn_adapter+0x15/0x20
> [    6.357228]  kthread+0xef/0x120
> [    6.357282]  ? __pfx_kthread+0x10/0x10
> [    6.357343]  ret_from_fork+0x2f/0x50
> [    6.357399]  ? __pfx_kthread+0x10/0x10
> [    6.357458]  ret_from_fork_asm+0x1b/0x30
> [    6.357560]  </TASK>
> [    6.357632] Modules linked in:
> [    6.357786] CR2: ffff9b10c0013cd0
> [    6.358010] ---[ end trace 0000000000000000 ]---

I get: 

[    2.423691] ------------[ cut here ]------------
[    2.424994] WARNING: CPU: 0 PID: 184 at mm/slab_common.c:992 free_large_kmalloc+0x4f/0x80
[    2.426183] Modules linked in:
[    2.426624] CPU: 0 PID: 184 Comm: kunit_try_catch Tainted: G                 N 6.5.0-rc4-next-20230731 #1
[    2.427964] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-debian-1.16.0-5 04/01/2014
[    2.429265] RIP: 0010:free_large_kmalloc+0x4f/0x80
[    2.429952] Code: f7 da 48 63 d2 48 8b 03 be 06 00 00 00 48 c1 e8 3a 48 8b 3c c5 60 ba 11 ab e8 0d 52 ff ff 89 ee 48 89 df 5b 5d e9 41 df 03 00 <0f> 0b 80 3d 49 43 e9 01 00 75
[    2.432511] RSP: 0000:ffffadcb0024bdb8 EFLAGS: 00010246
[    2.433259] RAX: 0100000000001000 RBX: ffffd16bc018aa40 RCX: ffffadcb0024bd7c
[    2.434262] RDX: ffffd16bc018aa48 RSI: ffffffffa96a9ec7 RDI: ffffd16bc018aa40
[    2.435265] RBP: ffffadcb0024be60 R08: 0000000000000001 R09: 0000000000000001
[    2.436269] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8a7084014410
[    2.437267] R13: ffff8a70840c4000 R14: 0000000000000002 R15: ffff8a70840564a8
[    2.438271] FS:  0000000000000000(0000) GS:ffff8a708f800000(0000) knlGS:0000000000000000
[    2.439403] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.440215] CR2: ffff8a7089401000 CR3: 0000000007a48001 CR4: 0000000000170ef0
[    2.441218] Call Trace:
[    2.441568]  <TASK>
[    2.441883]  ? free_large_kmalloc+0x4f/0x80
[    2.442491]  ? __warn+0x80/0x170
[    2.442988]  ? free_large_kmalloc+0x4f/0x80
[    2.443591]  ? report_bug+0x171/0x1a0
[    2.444145]  ? handle_bug+0x3c/0x70
[    2.444662]  ? exc_invalid_op+0x17/0x70
[    2.445225]  ? asm_exc_invalid_op+0x1a/0x20
[    2.445844]  ? kunit_add_action+0xc7/0x140
[    2.446455]  ? free_large_kmalloc+0x4f/0x80
[    2.447054]  kunit_filter_suites+0x468/0x480
[    2.447662]  ? kunit_add_action+0xc7/0x140
[    2.448258]  ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
[    2.449105]  filter_suites_test+0xea/0x2c0
[    2.449702]  kunit_generic_run_threadfn_adapter+0x15/0x20
[    2.450469]  kthread+0xf0/0x120
[    2.450940]  ? __pfx_kthread+0x10/0x10
[    2.451481]  ret_from_fork+0x2f/0x50
[    2.452012]  ? __pfx_kthread+0x10/0x10
[    2.452557]  ret_from_fork_asm+0x1b/0x30
[    2.453146]  </TASK>
[    2.453474] irq event stamp: 677
[    2.453943] hardirqs last  enabled at (689): [<ffffffffa911c24a>] console_unlock+0x10a/0x160
[    2.455151] hardirqs last disabled at (700): [<ffffffffa911c22f>] console_unlock+0xef/0x160
[    2.456329] softirqs last  enabled at (662): [<ffffffffa909179a>] irq_exit_rcu+0x7a/0xa0
[    2.457474] softirqs last disabled at (657): [<ffffffffa909179a>] irq_exit_rcu+0x7a/0xa0
[    2.458610] ---[ end trace 0000000000000000 ]---

But then it continues and eventually reaches:

Linux version 6.5.0-rc4-next-20230731 (root@ivb-ep) (gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP PREEMPT_DYNAMIC Mon Jul 31 15:39:05 CEST 2023
Network interface test passed
Boot successful.
/ #


Full log attached.

Attachment: log.gz
Description: application/gzip