From: syzbot ci <syzbot+cid08c37b8dadb4c43@syzkaller.appspotmail.com>
To: akpm@linux-foundation.org, axelrasmussen@google.com,
baohua@kernel.org, baolin.wang@linux.alibaba.com,
baoquan.he@linux.dev, cgroups@vger.kernel.org,
chengming.zhou@linux.dev, chrisl@kernel.org, corbet@lwn.net,
david@kernel.org, gourry@gourry.net, hannes@cmpxchg.org,
haowenchao22@gmail.com, hughd@google.com, kasong@tencent.com,
kernel-team@meta.com, kunwu.chan@linux.dev, liam@infradead.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, ljs@kernel.org, mhocko@kernel.org,
mkoutny@suse.com, muchun.song@linux.dev, nphamcs@gmail.com,
qi.zheng@linux.dev, riel@surriel.com, roman.gushchin@linux.dev,
rppt@kernel.org, shakeel.butt@linux.dev,
shikemeng@huaweicloud.com, skhan@linuxfoundation.org,
surenb@google.com, tj@kernel.org, vbabka@kernel.org,
weixugc@google.com, yosry@kernel.org, youngjun.park@lge.com,
yuanchu@google.com
Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com
Subject: [syzbot ci] Re: Virtual Swap Space (Swap Table Edition)
Date: Mon, 21 Sep 2026 06:42:16 -0700 [thread overview]
Message-ID: <6ab13438.71f81b7d.15fa6d.002c.GAE@google.com> (raw)
In-Reply-To: <20260918180241.3424851-1-nphamcs@gmail.com>
syzbot ci has tested the following series
[v5] Virtual Swap Space (Swap Table Edition)
https://lore.kernel.org/all/20260918180241.3424851-1-nphamcs@gmail.com
* [PATCH v5 01/11] mm, swap: add virtual swap device infrastructure
* [PATCH v5 02/11] mm, swap: support zswap and zero-filled swap pages as vswap backends
* [PATCH v5 03/11] mm, swap: prepare the swap IO path for vswap
* [PATCH v5 04/11] mm, swap: support physical swap as a vswap backend
* [PATCH v5 05/11] mm, swap: enable THP swapin for vswap entries
* [PATCH v5 06/11] mm, swap: write back vswap zswap entries to physical swap
* [PATCH v5 07/11] mm, swap: reclaim physical slots backing cache-only vswap entries
* [PATCH v5 08/11] mm, swap: only charge physical swap entries
* [PATCH v5 09/11] mm, swap: add debugfs counters for vswap
* [PATCH v5 10/11] mm, swap: defer memcg_table allocation for physical swap clusters
* [RFC PATCH v5 11/11] mm, swap: back vswap clusters with a VM_SPARSE array
and found the following issue:
KASAN: null-ptr-deref Read in swap_entry_backend_has_flag
Full report is available here:
https://ci.syzbot.org/series/713f2473-328a-4c16-8bce-63005d15a338
***
KASAN: null-ptr-deref Read in swap_entry_backend_has_flag
tree: linux-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
base: 27e4e1835109ef599d72abe6c09711e0b1916033
arch: amd64
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config: https://ci.syzbot.org/builds/26b06329-3b1c-4c73-8ee3-64c53b995186/config
syz repro: https://ci.syzbot.org/findings/f743742b-1934-4b4e-a590-9a36592da902/syz_repro
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_read include/linux/atomic/atomic-instrumented.h:3188 [inline]
BUG: KASAN: null-ptr-deref in __vtable_get mm/vswap.h:163 [inline]
BUG: KASAN: null-ptr-deref in vswap_to_phys mm/vswap.h:202 [inline]
BUG: KASAN: null-ptr-deref in swap_entry_backend_has_flag+0xea/0x210 mm/vswap.h:409
Read of size 8 at addr 0000000000000e00 by task syz.1.38/5916
CPU: 1 UID: 0 PID: 5916 Comm: syz.1.38 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
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
kasan_report+0x117/0x150 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
instrument_atomic_read include/linux/instrumented.h:82 [inline]
atomic_long_read include/linux/atomic/atomic-instrumented.h:3188 [inline]
__vtable_get mm/vswap.h:163 [inline]
vswap_to_phys mm/vswap.h:202 [inline]
swap_entry_backend_has_flag+0xea/0x210 mm/vswap.h:409
do_swap_page+0x767/0x5a20 mm/memory.c:5042
__collapse_huge_page_swapin mm/khugepaged.c:1152 [inline]
collapse_huge_page mm/khugepaged.c:1271 [inline]
mthp_collapse mm/khugepaged.c:1469 [inline]
collapse_run_pmd+0xaf1/0x5d90 mm/khugepaged.c:2811
madvise_collapse mm/madvise.c:1026 [inline]
madvise_vma_behavior+0x17cf/0x4d80 mm/madvise.c:1548
madvise_walk_vmas+0x576/0xb00 mm/madvise.c:1896
madvise_do_behavior+0x385/0x540 mm/madvise.c:2091
do_madvise+0x26f/0x330 mm/madvise.c:2189
__do_sys_madvise mm/madvise.c:2198 [inline]
__se_sys_madvise mm/madvise.c:2196 [inline]
__x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2196
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7b5939e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7b5a1ff028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f7b59625fa0 RCX: 00007f7b5939e159
RDX: 0000000000000019 RSI: 0000000000c00000 RDI: 0000200000000000
RBP: 00007f7b5943506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7b59626038 R14: 00007f7b59625fa0 R15: 00007ffe5f2d8d38
</TASK>
==================================================================
***
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@syzkaller.appspotmail.com
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.
To test a fix for this bug, please reply with `#syz test`
(on a separate line) and attach the patch to the email.
Notes:
- The patch will be applied on top of the tested series (as an
incremental fix).
- To test a new version of the whole series, please send it directly
to syzbot@lists.linux.dev.
- Arguments like custom git repos and branches are not supported.
next prev parent reply other threads:[~2026-09-21 13:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 18:02 [PATCH v5 00/11] " Nhat Pham
2026-09-18 18:02 ` [PATCH v5 01/11] mm, swap: add virtual swap device infrastructure Nhat Pham
2026-09-18 18:02 ` [PATCH v5 02/11] mm, swap: support zswap and zero-filled swap pages as vswap backends Nhat Pham
2026-09-18 18:02 ` [PATCH v5 03/11] mm, swap: prepare the swap IO path for vswap Nhat Pham
2026-09-18 18:02 ` [PATCH v5 04/11] mm, swap: support physical swap as a vswap backend Nhat Pham
2026-09-18 18:02 ` [PATCH v5 05/11] mm, swap: enable THP swapin for vswap entries Nhat Pham
2026-09-18 18:02 ` [PATCH v5 06/11] mm, swap: write back vswap zswap entries to physical swap Nhat Pham
2026-09-18 18:02 ` [PATCH v5 07/11] mm, swap: reclaim physical slots backing cache-only vswap entries Nhat Pham
2026-09-18 18:02 ` [PATCH v5 08/11] mm, swap: only charge physical swap entries Nhat Pham
2026-09-18 18:02 ` [PATCH v5 09/11] mm, swap: add debugfs counters for vswap Nhat Pham
2026-09-18 18:02 ` [PATCH v5 10/11] mm, swap: defer memcg_table allocation for physical swap clusters Nhat Pham
2026-09-18 18:02 ` [RFC PATCH v5 11/11] mm, swap: back vswap clusters with a VM_SPARSE array Nhat Pham
2026-09-18 18:38 ` [PATCH v5 00/11] Virtual Swap Space (Swap Table Edition) Nhat Pham
2026-09-21 13:42 ` syzbot ci [this message]
2026-09-21 19:00 ` [syzbot ci] " Nhat Pham
-- strict thread matches above, loose matches on Subject: below --
2026-08-06 18:42 [PATCH v3 00/11] " Nhat Pham
2026-08-07 5:26 ` [syzbot ci] " syzbot ci
2026-08-07 7:21 ` Chris Li
2026-08-10 16:33 ` Nhat Pham
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