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3936D60121; Fri, 20 Mar 2026 13:17:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6014C4CEF7; Fri, 20 Mar 2026 13:17:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774012670; bh=sS5dUb8WPlOcj7M/qOAafAQepwZu/bfgqgNiCm6w+8Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CtYoB3y30j9TjJgMFoD49UfnFLrlSld+STHYXHy0kRMzHdzwtT/+xIxEqfftEBSnz 3DqkuE1x+k/A+eqjJuNUH+8+FQUUeKhqsCUNx5hufzBFednrY57n5JiYHeWuJL8o8n GLPeDzmo8D4o2BU8f8LAMYufwoaoeVM1EMyR1D356Q5Cl3dHUFS+X4G5Bfar5rZAeV VKHu3CuUGXHAKpS5iAWaGPe7Hf4xtXCa/QtNcWKn5WEv03mICCkIpDvlqFsaMZW3f5 ElHConVDeXdd/GvU+HPLu0UnNmdW2DJ1J/WWP9bUN9ogq1szr8uIqhNrOQzulA0thG 3E2mZfQpyGCUw== Date: Fri, 20 Mar 2026 13:17:45 +0000 From: "Lorenzo Stoakes (Oracle)" To: syzbot Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@kernel.org, dev.jain@arm.com, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npache@redhat.com, ryan.roberts@arm.com, syzkaller-bugs@googlegroups.com, ziy@nvidia.com Subject: Re: [syzbot] [mm?] kernel BUG in collapse_scan_file Message-ID: <6ff97738-33f9-4450-adf8-c3cf251d82c7@lucifer.local> References: <69bba3c0.050a0220.227207.002b.GAE@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <69bba3c0.050a0220.227207.002b.GAE@google.com> X-Stat-Signature: nwp8gdaatz6b5q9w7c8wxzn6iux7bcy3 X-Rspam-User: X-Rspamd-Queue-Id: E05DF180011 X-Rspamd-Server: rspam12 X-HE-Tag: 1774012671-549526 X-HE-Meta: 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 YcCNy1iq 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 +EjVC9Q5 6donbXmRZjjrNoBXnoLqz8/5GPNG2PU2PUken/KA6gyFN/nI5fiz27sblkjRokgC/zeVvOxq8baB0XkocpERzbtLVjuvWTkVlkegPZYXsJl76LDZD9aVEpPoZylN5NCuytFh0dbv0iI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 19, 2026 at 12:20:32AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 95c541ddfb08 Add linux-next specific files for 20260316 This is pre- Mark dropping the xarray thing from the tree.... > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=15ccc216580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ed431987028345c6 > dashboard link: https://syzkaller.appspot.com/bug?extid=8961cb270ae74b4129fb > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f778da580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12cc006a580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/c40f27ad73d8/disk-95c541dd.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/bd811888f684/vmlinux-95c541dd.xz > kernel image: https://storage.googleapis.com/syzbot-assets/3b72363d7dbd/bzImage-95c541dd.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+8961cb270ae74b4129fb@syzkaller.appspotmail.com > > node ffff88805d558b00 offset 0 parent ffff88805d558840 shift 0 count 3 values 0 array ffff88807a8195c0 list ffff88805d558b18 ffff88805d558b18 marks 0 0 0 > ------------[ cut here ]------------ > kernel BUG at ./include/linux/xarray.h:1441! ...Presumably the same potentially broken xarray debug we were discussing in [0]. [0]:https://lore.kernel.org/linux-mm/69bba3c0.050a0220.227207.002b.GAE@google.com/ Cheers, Lorenzo > Oops: invalid opcode: 0000 [#1] SMP KASAN PTI > CPU: 0 UID: 0 PID: 6001 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 > RIP: 0010:XAS_INVALID include/linux/xarray.h:1441 [inline] > RIP: 0010:collapse_file mm/khugepaged.c:2055 [inline] > RIP: 0010:collapse_scan_file+0x4f98/0x5230 mm/khugepaged.c:2404 > Code: ff 4c 89 e7 48 c7 c6 60 b2 dc 8b e8 82 62 f1 fe 90 0f 0b 48 85 db 0f 84 03 01 00 00 e8 71 e5 8f ff 48 89 df e8 a9 20 7b 09 90 <0f> 0b e8 61 e5 8f ff 48 89 df 48 c7 c6 60 b2 dc 8b e8 52 62 f1 fe > RSP: 0018:ffffc90003826e20 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff88805d558b00 RCX: a13f20bd39c5a100 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: ffffc90003827130 R08: ffffc90003826ba7 R09: 1ffff92000704d74 > R10: dffffc0000000000 R11: fffff52000704d75 R12: ffffea0001b678f0 > R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc90003827010 > FS: 000055557e3c2500(0000) GS:ffff888125437000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000020000000b000 CR3: 000000007ac66000 CR4: 00000000003526f0 > Call Trace: > > collapse_single_pmd+0x22b/0x4510 mm/khugepaged.c:2437 > madvise_collapse+0x34c/0x820 mm/khugepaged.c:2859 > madvise_vma_behavior+0x1094/0x4460 mm/madvise.c:1362 > madvise_walk_vmas+0x573/0xae0 mm/madvise.c:1711 > madvise_do_behavior+0x386/0x540 mm/madvise.c:1927 > do_madvise+0x1fa/0x2e0 mm/madvise.c:2020 > __do_sys_madvise mm/madvise.c:2029 [inline] > __se_sys_madvise mm/madvise.c:2027 [inline] > __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2027 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f90d419c799 > 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:00007ffd50711398 EFLAGS: 00000246 ORIG_RAX: 000000000000001c > RAX: ffffffffffffffda RBX: 00007f90d4415fa0 RCX: 00007f90d419c799 > RDX: 0000000000000019 RSI: 0000000000600003 RDI: 0000200000000000 > RBP: 00007f90d4232c99 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f90d4415fac R14: 00007f90d4415fa0 R15: 00007f90d4415fa0 > > Modules linked in: > ---[ end trace 0000000000000000 ]--- > RIP: 0010:XAS_INVALID include/linux/xarray.h:1441 [inline] > RIP: 0010:collapse_file mm/khugepaged.c:2055 [inline] > RIP: 0010:collapse_scan_file+0x4f98/0x5230 mm/khugepaged.c:2404 > Code: ff 4c 89 e7 48 c7 c6 60 b2 dc 8b e8 82 62 f1 fe 90 0f 0b 48 85 db 0f 84 03 01 00 00 e8 71 e5 8f ff 48 89 df e8 a9 20 7b 09 90 <0f> 0b e8 61 e5 8f ff 48 89 df 48 c7 c6 60 b2 dc 8b e8 52 62 f1 fe > RSP: 0018:ffffc90003826e20 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff88805d558b00 RCX: a13f20bd39c5a100 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: ffffc90003827130 R08: ffffc90003826ba7 R09: 1ffff92000704d74 > R10: dffffc0000000000 R11: fffff52000704d75 R12: ffffea0001b678f0 > R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc90003827010 > FS: 000055557e3c2500(0000) GS:ffff888125537000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f8156602000 CR3: 000000007ac66000 CR4: 00000000003526f0 > > > --- > 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 syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. > > 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