linux-kernel - [syzbot ci] Re: mm/slub: Removing unnecessary variable accesses in the get

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Message-ID: <68c13941.050a0220.3c6139.001d.GAE@google.com>
Date: Wed, 10 Sep 2025 01:39:29 -0700
From: syzbot ci <syzbot+ci49ef42f07c0503e6@...kaller.appspotmail.com>
To: 42.hyeyoo@...il.com, akpm@...ux-foundation.org, cl@...ux.com, 
	iamjoonsoo.kim@....com, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	penberg@...nel.org, rgbi3307@...il.com, rgbi3307@...er.com, 
	rientjes@...gle.com, roman.gushchin@...ux.dev, vbabka@...e.cz
Cc: syzbot@...ts.linux.dev, syzkaller-bugs@...glegroups.com
Subject: [syzbot ci] Re: mm/slub: Removing unnecessary variable accesses in
 the get_freelist()

syzbot ci has tested the following series

[v1] mm/slub: Removing unnecessary variable accesses in the get_freelist()
https://lore.kernel.org/all/20250910005957.54108-1-rgbi3307@gmail.com
* [PATCH] mm/slub: Removing unnecessary variable accesses in the get_freelist()

and found the following issue:
kernel BUG in __smpboot_create_thread

Full report is available here:
https://ci.syzbot.org/series/832d6128-4556-4bd1-ab18-0676b8e7dbc1

***

kernel BUG in __smpboot_create_thread

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      f777d1112ee597d7f7dd3ca232220873a34ad0c8
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/7bff7792-4edd-4680-a5e7-3cc9d97ac5ed/config

smpboot: CPU0: Intel QEMU Virtual CPU version 2.5+ (family: 0xf, model: 0x6b, stepping: 0x1)
Performance Events: unsupported Netburst CPU model 107 no PMU driver, software events only.
signal: max sigframe size: 1440
------------[ cut here ]------------
kernel BUG at mm/slub.c:3832!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:___slab_alloc+0x13ab/0x1420
Code: ff ff 4c 89 e7 48 c7 c6 3a a1 a0 8d e8 3e 4f 0f ff 90 0f 0b 90 0f 0b 48 89 f7 48 c7 c6 3a a1 a0 8d e8 29 4f 0f ff 90 0f 0b 90 <0f> 0b 90 0f 0b 4c 89 e7 48 c7 c6 3a a1 a0 8d e8 11 4f 0f ff 90 0f
RSP: 0000:ffffc90000047750 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff888100028000 RCX: 0000000000800001
RDX: 0000000000800001 RSI: ffffffff8dba8965 RDI: ffffffff8be33980
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff82189e55
R10: dffffc0000000000 R11: fffffbfff1f47407 R12: ffff88804b03e480
R13: ffff88801a441640 R14: ffff88804b03e460 R15: ffffffff82189e55
FS:  0000000000000000(0000) GS:ffff8880b8615000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88813ffff000 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __kmalloc_cache_node_noprof+0x29a/0x3d0
 __smpboot_create_thread+0x11a/0x3b0
 smpboot_register_percpu_thread+0xc6/0x420
 spawn_ksoftirqd+0x2f/0xc0
 do_one_initcall+0x236/0x820
 do_pre_smp_initcalls+0x4c/0x80
 kernel_init_freeable+0x30c/0x4b0
 kernel_init+0x1d/0x1d0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:___slab_alloc+0x13ab/0x1420
Code: ff ff 4c 89 e7 48 c7 c6 3a a1 a0 8d e8 3e 4f 0f ff 90 0f 0b 90 0f 0b 48 89 f7 48 c7 c6 3a a1 a0 8d e8 29 4f 0f ff 90 0f 0b 90 <0f> 0b 90 0f 0b 4c 89 e7 48 c7 c6 3a a1 a0 8d e8 11 4f 0f ff 90 0f
RSP: 0000:ffffc90000047750 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff888100028000 RCX: 0000000000800001
RDX: 0000000000800001 RSI: ffffffff8dba8965 RDI: ffffffff8be33980
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff82189e55
R10: dffffc0000000000 R11: fffffbfff1f47407 R12: ffff88804b03e480
R13: ffff88801a441640 R14: ffff88804b03e460 R15: ffffffff82189e55
FS:  0000000000000000(0000) GS:ffff8880b8615000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88813ffff000 CR3: 000000000df36000 CR4: 00000000000006f0


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@...kaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@...glegroups.com.