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Mon, 22 Jun 2026 09:23:37 -0700 (PDT) Date: Mon, 22 Jun 2026 09:23:37 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a396189.af26c8ab.2133ed.0002.GAE@google.com> Subject: [moderation/CI] Re: mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access From: syzbot ci To: syzkaller-upstream-moderation@googlegroups.com Cc: syzbot@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable syzbot ci has tested the following series [v2] mm: page_ext: add count limit to page_ext_iter_next to prevent invalid= PFN access https://lore.kernel.org/all/20260622-page_ext-v2-1-135d4cfbc42f@oss.qualcom= m.com * [PATCH v2] mm: page_ext: add count limit to page_ext_iter_next to prevent= invalid PFN access and found the following issue: WARNING in depot_fetch_stack Full report is available here: https://ci.syzbot.org/series/092dd7dc-cb78-46b6-8703-6044fff2631d *** WARNING in depot_fetch_stack tree: mm-new URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm= .git base: e1201ff76176ef666b13d1a4ec6b6190ddc6abc8 arch: amd64 compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp= 1~20260514074407.73), Debian LLD 22.1.6 config: https://ci.syzbot.org/builds/18f461a2-7098-44bc-9d42-634b56ba48d= 9/config ------------[ cut here ]------------ !refcount_read(&stack->count) WARNING: lib/stackdepot.c:517 at depot_fetch_stack+0x91/0xa0, CPU#0: kworke= r/u9:4/1114 Modules linked in: CPU: 0 UID: 0 PID: 1114 Comm: kworker/u9:4 Not tainted syzkaller #0 PREEMPT= (full)=20 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16= .2-1 04/01/2014 Workqueue: events_unbound call_usermodehelper_exec_work RIP: 0010:depot_fetch_stack+0x91/0xa0 Code: 39 f5 72 d0 48 8d 3d 7e 1b 4d 0b 89 ee 44 89 f2 89 d9 67 48 0f b9 3a = 31 c0 5b 41 5e 5d e9 87 67 b8 06 cc 90 0f 0b 90 eb ee 90 <0f> 0b 90 eb e8 6= 6 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 RSP: 0000:ffffc900079a6ce0 EFLAGS: 00010246 RAX: ffff888168b94000 RBX: 0000000000000ce0 RCX: 0000000000000067 RDX: 0000000000000000 RSI: ffffffff8e215937 RDI: ffffffff8c28ab20 RBP: 0000000000000067 R08: ffff88810495a407 R09: 1ffff1102092b480 R10: dffffc0000000000 R11: ffffed102092b481 R12: 00000000019c0068 R13: 0000000000000001 R14: 000000000000010f R15: ffff88810afb1dc0 FS: 0000000000000000(0000) GS:ffff88818dcb5000(0000) knlGS:000000000000000= 0 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88823ffff000 CR3: 000000000e74a000 CR4: 00000000000006f0 Call Trace: __set_page_owner+0x140/0x4c0 post_alloc_hook+0x1f9/0x250 get_page_from_freelist+0x21fa/0x2270 __alloc_frozen_pages_noprof+0x18d/0x380 alloc_pages_mpol+0x212/0x380 alloc_pages_noprof+0xac/0x2a0 get_free_pages_noprof+0xf/0x80 __kasan_populate_vmalloc+0x38/0x1c0 alloc_vmap_area+0xd1a/0x1420 __get_vm_area_node+0x1f2/0x300 __vmalloc_node_range_noprof+0x358/0x1730 __vmalloc_node_noprof+0xc2/0x100 dup_task_struct+0x28e/0x830 copy_process+0x79d/0x4380 kernel_clone+0x2d7/0x940 user_mode_thread+0x110/0x180 call_usermodehelper_exec_work+0x5c/0x230 process_scheduled_works+0xa8e/0x14e0 worker_thread+0xa47/0xfb0 kthread+0x389/0x470 ret_from_fork+0x514/0xb70 ret_from_fork_asm+0x1a/0x30 *** 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 patch for this bug, please reply with `#syz test` (should be on a separate line). The patch should be attached to the email. Note: arguments like custom git repos and branches are not supported. The email will later be sent to: [akpm@linux-foundation.org david@kernel.org hannes@cmpxchg.org jackmanb@goo= gle.com kernel@oss.qualcomm.com ketan.kishore@oss.qualcomm.com liam@infrade= ad.org linux-kernel@vger.kernel.org linux-mm@kvack.org ljs@kernel.org luizc= ap@redhat.com mhocko@suse.com rppt@kernel.org stable@vger.kernel.org surenb= @google.com vbabka@kernel.org willy@infradead.org ziy@nvidia.com] If the report looks fine to you, reply with: #syz upstream If the report is a false positive, reply with #syz invalid