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AJvYcCUnBC6ePdaFZezwod9V4KjKgv/Vy1cYHqFpph5FVr4mTgVBFWDWth1sMfvHrKhribrJmnnkN8Q=@lists.linux.dev X-Gm-Message-State: AOJu0Yy9F6YGYB6tnhLb6Op95NLyrNXX0gZQIwYQVelEu4tMTQYiBMz3 AL9I87dpt6lBND1934j1dNG613D059c7kbl5qbN5+sCamaO0RWW2NnDfBpAeZY6QYgnaDcM0VCz gxSrtglgx4fx8weOOOcDmd8b8lMAd8lubmkTufSkYbcXKxA4MwgvGzABoapE= X-Google-Smtp-Source: AGHT+IHIYFLsAiBCqojPIt2QDWa9d/yLxjivS9JM+BHMWwChpQQKGmD61OncOVmQEwUwcLFJDz83jDyr5DBAP7ALsrxrwXOp6FZQ Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:1f13:b0:42e:7589:6290 with SMTP id e9e14a558f8ab-432f8fbe8b4mr61708075ab.12.1761768267270; Wed, 29 Oct 2025 13:04:27 -0700 (PDT) Date: Wed, 29 Oct 2025 13:04:27 -0700 In-Reply-To: <68cd66b0.050a0220.139b6.000f.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6902734b.050a0220.3344a1.0430.GAE@google.com> Subject: Re: [syzbot] [kvmarm?] kernel BUG in kvm_s2_put_page From: syzbot To: catalin.marinas@arm.com, joey.gouly@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, suzuki.poulose@arm.com, syzkaller-bugs@googlegroups.com, will@kernel.org, yuzenghui@huawei.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 10fd0285305d Merge branch kvm-arm64/selftests-6.18 into kv.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next console output: https://syzkaller.appspot.com/x/log.txt?x=173e4fe2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a4522b3a704e0394 dashboard link: https://syzkaller.appspot.com/bug?extid=c41f3ddb8299a30a98b5 compiler: Debian clang version 20.1.8 (++20250708123704+0de59a293f7a-1~exp1~20250708003721.134), Debian LLD 20.1.8 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13559c92580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12963fe2580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-10fd0285.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/65e2ebd050e3/vmlinux-10fd0285.xz kernel image: https://storage.googleapis.com/syzbot-assets/9d47fc3df12e/Image-10fd0285.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c41f3ddb8299a30a98b5@syzkaller.appspotmail.com raw: 01fff1c000000000 ffffc1ffc08742c8 ffffc1ffc07b2488 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) ------------[ cut here ]------------ kernel BUG at ./include/linux/mm.h:1036! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP Modules linked in: CPU: 0 UID: 0 PID: 3630 Comm: syz.2.17 Not tainted syzkaller #0 PREEMPT Hardware name: linux,dummy-virt (DT) pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : put_page_testzero include/linux/mm.h:1036 [inline] pc : folio_put_testzero include/linux/mm.h:1042 [inline] pc : folio_put include/linux/mm.h:1359 [inline] pc : put_page include/linux/mm.h:1429 [inline] pc : kvm_s2_put_page+0x374/0x3a0 arch/arm64/kvm/mmu.c:264 lr : put_page_testzero include/linux/mm.h:1036 [inline] lr : folio_put_testzero include/linux/mm.h:1042 [inline] lr : folio_put include/linux/mm.h:1359 [inline] lr : put_page include/linux/mm.h:1429 [inline] lr : kvm_s2_put_page+0x374/0x3a0 arch/arm64/kvm/mmu.c:264 sp : ffff80008e717450 x29: ffff80008e717450 x28: bff000001ec92000 x27: bff000001ec92000 x26: 00000000000000ff x25: ffff800087396000 x24: ffffc1ffc0000000 x23: ffffc1ffc0874288 x22: 0000000000000000 x21: ffffc1ffc08742b4 x20: 0000000000000000 x19: ffffc1ffc0874280 x18: 00000000fb20c077 x17: 00000000057d7f34 x16: 00000000fb1a5197 x15: 00000000866b9677 x14: ffffffffffffffff x13: fff0000015a39d88 x12: 0000000000000001 x11: 0000000000000000 x10: 0000000000ff0100 x9 : a6a806ed1668b300 x8 : a6a806ed1668b300 x7 : ffff80008039fbc8 x6 : 0000000000000000 x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff80008074aff8 x2 : 0000000000000001 x1 : 0000000100000000 x0 : 000000000000003e Call trace: put_page_testzero include/linux/mm.h:1036 [inline] (P) folio_put_testzero include/linux/mm.h:1042 [inline] (P) folio_put include/linux/mm.h:1359 [inline] (P) put_page include/linux/mm.h:1429 [inline] (P) kvm_s2_put_page+0x374/0x3a0 arch/arm64/kvm/mmu.c:264 (P) stage2_free_walker+0x1b0/0x264 arch/arm64/kvm/hyp/pgtable.c:1549 kvm_pgtable_visitor_cb arch/arm64/kvm/hyp/pgtable.c:130 [inline] __kvm_pgtable_visit arch/arm64/kvm/hyp/pgtable.c:212 [inline] __kvm_pgtable_walk+0x7d8/0xa68 arch/arm64/kvm/hyp/pgtable.c:237 _kvm_pgtable_walk arch/arm64/kvm/hyp/pgtable.c:260 [inline] kvm_pgtable_walk+0x294/0x468 arch/arm64/kvm/hyp/pgtable.c:283 kvm_pgtable_stage2_destroy_range+0x60/0xb4 arch/arm64/kvm/hyp/pgtable.c:1563 stage2_destroy_range arch/arm64/kvm/mmu.c:924 [inline] kvm_stage2_destroy arch/arm64/kvm/mmu.c:935 [inline] kvm_free_stage2_pgd+0x198/0x28c arch/arm64/kvm/mmu.c:1112 kvm_uninit_stage2_mmu+0x20/0x38 arch/arm64/kvm/mmu.c:1023 kvm_arch_flush_shadow_all+0x1a8/0x1e0 arch/arm64/kvm/nested.c:1113 kvm_flush_shadow_all virt/kvm/kvm_main.c:343 [inline] kvm_mmu_notifier_release+0x48/0xa8 virt/kvm/kvm_main.c:884 mn_hlist_release mm/mmu_notifier.c:321 [inline] __mmu_notifier_release+0x310/0x614 mm/mmu_notifier.c:359 mmu_notifier_release include/linux/mmu_notifier.h:402 [inline] exit_mmap+0xb8/0xbb8 mm/mmap.c:1263 __mmput+0x10c/0x528 kernel/fork.c:1130 mmput+0x70/0xac kernel/fork.c:1152 exit_mm+0x158/0x258 kernel/exit.c:582 do_exit+0x788/0x2378 kernel/exit.c:949 do_group_exit+0x1d4/0x2ac kernel/exit.c:1102 get_signal+0x1440/0x1554 kernel/signal.c:3034 do_signal+0x23c/0x4dd0 arch/arm64/kernel/signal.c:1618 do_notify_resume+0xb0/0x270 arch/arm64/kernel/entry-common.c:152 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:173 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:182 [inline] el0_svc+0xb8/0x164 arch/arm64/kernel/entry-common.c:880 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 Code: 900377c1 910e9421 aa1303e0 97f9c9f2 (d4210000) ---[ end trace 0000000000000000 ]--- --- 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.