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Message-ID: <68f11c1a.050a0220.91a22.0411.GAE@google.com>
Date: Thu, 16 Oct 2025 09:23:54 -0700
From: syzbot ci <syzbot+ci290b7e46a3349a6e@...kaller.appspotmail.com>
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Cc: syzbot@...ts.linux.dev, syzkaller-bugs@...glegroups.com
Subject: [syzbot ci] Re: mm: add huge pfnmap support for remap_pfn_range()
syzbot ci has tested the following series
[v2] mm: add huge pfnmap support for remap_pfn_range()
https://lore.kernel.org/all/20251016112704.179280-1-yintirui@huawei.com
* [PATCH RFC 1/2] pgtable: add pte_clrhuge() implementation for arm64 and riscv
* [PATCH RFC 2/2] mm: add PMD-level huge page support for remap_pfn_range()
and found the following issue:
stack segment fault in pgtable_trans_huge_withdraw
Full report is available here:
https://ci.syzbot.org/series/d04c2914-0d99-4132-89d4-899e22abf904
***
stack segment fault in pgtable_trans_huge_withdraw
tree: torvalds
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base: 3a8660878839faadb4f1a6dd72c3179c1df56787
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/9d7864e5-ad3a-4c0d-b21d-86cfc476792e/config
C repro: https://ci.syzbot.org/findings/b9fca361-413d-4db1-b8b2-1849cd2c50dd/c_repro
syz repro: https://ci.syzbot.org/findings/b9fca361-413d-4db1-b8b2-1849cd2c50dd/syz_repro
Oops: stack segment: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 5968 Comm: syz.0.17 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:pgtable_trans_huge_withdraw+0x115/0x310 mm/pgtable-generic.c:188
Code: c3 10 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 9d e9 13 00 48 8b 03 48 89 04 24 4c 8d 78 08 4c 89 fd 48 c1 ed 03 <42> 80 7c 2d 00 00 74 08 4c 89 ff e8 7b e9 13 00 49 8b 07 48 8d 48
RSP: 0018:ffffc90003717300 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffea00044848d0 RCX: ffff88816c890000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff88816db66a23 R09: 1ffff1102db6cd44
R10: dffffc0000000000 R11: ffffed102db6cd45 R12: ffff888112123000
R13: dffffc0000000000 R14: ffff888112123000 R15: 0000000000000008
FS: 000055556cb5f500(0000) GS:ffff88818e70c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001102a4000 CR4: 00000000000006f0
Call Trace:
<TASK>
zap_deposited_table mm/huge_memory.c:2169 [inline]
zap_huge_pmd+0xa25/0xf50 mm/huge_memory.c:2197
zap_pmd_range mm/memory.c:1926 [inline]
zap_pud_range mm/memory.c:1975 [inline]
zap_p4d_range mm/memory.c:1996 [inline]
unmap_page_range+0x9fe/0x4370 mm/memory.c:2017
unmap_single_vma mm/memory.c:2060 [inline]
unmap_vmas+0x399/0x580 mm/memory.c:2104
exit_mmap+0x240/0xb40 mm/mmap.c:1280
__mmput+0x118/0x430 kernel/fork.c:1133
copy_process+0x2910/0x3c00 kernel/fork.c:2460
kernel_clone+0x21e/0x840 kernel/fork.c:2609
__do_sys_clone kernel/fork.c:2750 [inline]
__se_sys_clone kernel/fork.c:2734 [inline]
__x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2734
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f946958eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc41c94258 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f94697e5fa0 RCX: 00007f946958eec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000002001000
RBP: 00007f9469611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f94697e5fa0 R14: 00007f94697e5fa0 R15: 0000000000000006
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pgtable_trans_huge_withdraw+0x115/0x310 mm/pgtable-generic.c:188
Code: c3 10 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 9d e9 13 00 48 8b 03 48 89 04 24 4c 8d 78 08 4c 89 fd 48 c1 ed 03 <42> 80 7c 2d 00 00 74 08 4c 89 ff e8 7b e9 13 00 49 8b 07 48 8d 48
RSP: 0018:ffffc90003717300 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffea00044848d0 RCX: ffff88816c890000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff88816db66a23 R09: 1ffff1102db6cd44
R10: dffffc0000000000 R11: ffffed102db6cd45 R12: ffff888112123000
R13: dffffc0000000000 R14: ffff888112123000 R15: 0000000000000008
FS: 000055556cb5f500(0000) GS:ffff88818e70c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001102a4000 CR4: 00000000000006f0
----------------
Code disassembly (best guess):
0: c3 ret
1: 10 48 89 adc %cl,-0x77(%rax)
4: d8 48 c1 fmuls -0x3f(%rax)
7: e8 03 42 80 3c call 0x3c80420f
c: 28 00 sub %al,(%rax)
e: 74 08 je 0x18
10: 48 89 df mov %rbx,%rdi
13: e8 9d e9 13 00 call 0x13e9b5
18: 48 8b 03 mov (%rbx),%rax
1b: 48 89 04 24 mov %rax,(%rsp)
1f: 4c 8d 78 08 lea 0x8(%rax),%r15
23: 4c 89 fd mov %r15,%rbp
26: 48 c1 ed 03 shr $0x3,%rbp
* 2a: 42 80 7c 2d 00 00 cmpb $0x0,0x0(%rbp,%r13,1) <-- trapping instruction
30: 74 08 je 0x3a
32: 4c 89 ff mov %r15,%rdi
35: e8 7b e9 13 00 call 0x13e9b5
3a: 49 8b 07 mov (%r15),%rax
3d: 48 rex.W
3e: 8d .byte 0x8d
3f: 48 rex.W
***
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.
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