From: Andrew Morton <akpm@linux-foundation•org>
To: syzbot <syzbot+8ffca916f3fa5455f9b4@syzkaller•appspotmail.com>
Cc: apopple@nvidia•com, byungchul@sk•com, david@kernel•org,
gourry@gourry•net, joshua.hahnjy@gmail•com,
linux-kernel@vger•kernel.org, linux-mm@kvack•org,
linux-next@vger•kernel.org, matthew.brost@intel•com,
rakie.kim@sk•com, sfr@canb•auug.org.au,
syzkaller-bugs@googlegroups•com, ying.huang@linux•alibaba.com,
ziy@nvidia•com, "Michael S . Tsirkin" <mst@redhat•com>
Subject: Re: [syzbot] [mm?] linux-next test error: kernel BUG in post_alloc_hook
Date: Wed, 3 Jun 2026 15:47:37 -0700 [thread overview]
Message-ID: <20260603154737.48dfcc19a51da03241e1af48@linux-foundation.org> (raw)
In-Reply-To: <6a20a309.85ccb786.283107.0005.GAE@google.com>
(cc Mike Tsirkin)
On Wed, 03 Jun 2026 14:56:25 -0700 syzbot <syzbot+8ffca916f3fa5455f9b4@syzkaller•appspotmail.com> wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: a225caacc365 Add linux-next specific files for 20260603
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13b0de66580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=717edf2a5f9fc390
> dashboard link: https://syzkaller.appspot.com/bug?extid=8ffca916f3fa5455f9b4
> compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f799d07ea17d/disk-a225caac.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/72d0f0ff94e6/vmlinux-a225caac.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/99d4279e6fec/bzImage-a225caac.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8ffca916f3fa5455f9b4@syzkaller•appspotmail.com
>
> ...
>
> **********************************************************
> ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
> ** **
> ** This system shows unhashed kernel memory addresses **
> ** via the console, logs, and other interfaces. This **
> ** might reduce the security of your system. **
> ** **
> ** If you see this message and you are not debugging **
> ** the kernel, report this immediately to your system **
> ** administrator! **
> ** **
> ** Use hash_pointers=always to force this mode off **
> ** **
> ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
> **********************************************************
Geeze, who added that.
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x13fe38
> head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x100000000000040(head|node=0|zone=2)
> raw: 0100000000000040 dead000000000100 dead000000000122 0000000000000000
> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> head: 0100000000000040 dead000000000100 dead000000000122 0000000000000000
> head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> head: 0100000000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
> head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000004
> page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
> ------------[ cut here ]------------
> kernel BUG at ./include/linux/page-flags.h:682!
> Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
> CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted syzkaller #0 PREEMPT_{RT,(undef)}
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
> RIP: 0010:__ClearPagePrezeroed include/linux/page-flags.h:682 [inline]
> RIP: 0010:post_alloc_hook+0x287/0x310 mm/page_alloc.c:1863
That's the __ClearPagePrezeroed(page) added by 504f40f6bda6 ("mm:
page_reporting: skip redundant zeroing of host-zeroed reported pages").
Was it intended that this series
(https://lore.kernel.org/cover.1779315441.git.mst@redhat.com) be
included in -next? It's huge, it's late, review is minor.
<remainder of report is below>
> Code: ff ff 89 da be 01 00 00 00 48 c7 c7 40 50 4f 8e e8 ce 4b d4 02 e9 c5 fe ff ff 4c 89 ef 48 c7 c6 40 ef 7a 8b e8 2a c6 05 ff 90 <0f> 0b 31 ed f7 44 24 04 00 01 00 00 0f 84 8e fd ff ff e9 86 fd ff
> RSP: 0000:ffffffff8e0078e0 EFLAGS: 00010046
> RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffffffff8e0fef40
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
> R10: dffffc0000000000 R11: ffffed10170c4903 R12: dffffc0000000000
> R13: ffffea0004ff8e00 R14: 1ffffd40009ff1c0 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff888125a79000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffff88823ffff000 CR3: 000000000e1b8000 CR4: 00000000000100b0
> Call Trace:
> <TASK>
> prep_new_page mm/page_alloc.c:1925 [inline]
> get_page_from_freelist+0x3081/0x3320 mm/page_alloc.c:4015
> __alloc_frozen_pages_noprof+0x194/0x380 mm/page_alloc.c:5376
> __alloc_pages_mpol+0xe0/0x390 mm/mempolicy.c:2495
> alloc_slab_page mm/slub.c:3287 [inline]
> allocate_slab+0x83/0x5e0 mm/slub.c:3404
> new_slab mm/slub.c:3447 [inline]
> ___slab_alloc+0x160/0x930 mm/slub.c:4485
> __slab_alloc_node mm/slub.c:4549 [inline]
> slab_alloc_node mm/slub.c:4925 [inline]
> __do_kmalloc_node mm/slub.c:5331 [inline]
> __kmalloc_noprof+0x140/0x7b0 mm/slub.c:5345
> _kmalloc_noprof include/linux/slab.h:973 [inline]
> _kzalloc_noprof include/linux/slab.h:1286 [inline]
> __alloc_empty_sheaf mm/slub.c:2774 [inline]
> alloc_empty_sheaf mm/slub.c:2794 [inline]
> init_percpu_sheaves mm/slub.c:7555 [inline]
> do_kmem_cache_create+0x8ae/0x9a0 mm/slub.c:8595
> create_boot_cache+0xbf/0x120 mm/slab_common.c:717
> create_kmalloc_cache+0x41/0xb0 mm/slab_common.c:735
> new_kmalloc_cache+0xd4/0x180 mm/slab_common.c:982
> create_kmalloc_caches+0x14/0x50 mm/slab_common.c:1005
> kmem_cache_init+0x14a/0x1e0 mm/slub.c:8496
> mm_core_init+0x7e/0xb0 mm/mm_init.c:2728
> start_kernel+0x162/0x3e0 init/main.c:1034
> x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
> x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
> common_startup_64+0x13e/0x157
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__ClearPagePrezeroed include/linux/page-flags.h:682 [inline]
> RIP: 0010:post_alloc_hook+0x287/0x310 mm/page_alloc.c:1863
> Code: ff ff 89 da be 01 00 00 00 48 c7 c7 40 50 4f 8e e8 ce 4b d4 02 e9 c5 fe ff ff 4c 89 ef 48 c7 c6 40 ef 7a 8b e8 2a c6 05 ff 90 <0f> 0b 31 ed f7 44 24 04 00 01 00 00 0f 84 8e fd ff ff e9 86 fd ff
> RSP: 0000:ffffffff8e0078e0 EFLAGS: 00010046
> RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffffffff8e0fef40
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
> R10: dffffc0000000000 R11: ffffed10170c4903 R12: dffffc0000000000
> R13: ffffea0004ff8e00 R14: 1ffffd40009ff1c0 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff888125a79000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffff88823ffff000 CR3: 000000000e1b8000 CR4: 00000000000100b0
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups•com.
>
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>
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next prev parent reply other threads:[~2026-06-03 22:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 21:56 [syzbot] [mm?] linux-next test error: kernel BUG in post_alloc_hook syzbot
2026-06-03 22:47 ` Andrew Morton [this message]
2026-06-04 4:14 ` Michael S. Tsirkin
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