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[80.230.25.45]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490bc23394asm39489705e9.0.2026.06.03.21.14.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jun 2026 21:14:39 -0700 (PDT) Date: Thu, 4 Jun 2026 00:14:35 -0400 From: "Michael S. Tsirkin" To: Andrew Morton Cc: syzbot , 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 Subject: Re: [syzbot] [mm?] linux-next test error: kernel BUG in post_alloc_hook Message-ID: <20260604001334-mutt-send-email-mst@kernel.org> References: <6a20a309.85ccb786.283107.0005.GAE@google.com> <20260603154737.48dfcc19a51da03241e1af48@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-next@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260603154737.48dfcc19a51da03241e1af48@linux-foundation.org> On Wed, Jun 03, 2026 at 03:47:37PM -0700, Andrew Morton wrote: > (cc Mike Tsirkin) > > On Wed, 03 Jun 2026 14:56:25 -0700 syzbot 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. Of course not ( I've no idea how that happened. Should not push to next late at night. > > > > 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: > > > > 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 > > > > 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. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > If the report is already addressed, let syzbot know by replying with: > > #syz fix: exact-commit-title > > > > If you want to overwrite report's subsystems, reply with: > > #syz set subsystems: new-subsystem > > (See the list of subsystem names on the web dashboard) > > > > If the report is a duplicate of another one, reply with: > > #syz dup: exact-subject-of-another-report > > > > If you want to undo deduplication, reply with: > > #syz undup