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Fri, 22 Aug 2025 20:30:58 -0700 (PDT) Received: from dw-tp ([171.76.85.35]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-24668879763sm10092605ad.108.2025.08.22.20.30.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Aug 2025 20:30:57 -0700 (PDT) From: Ritesh Harjani (IBM) To: Andrew Morton , syzbot Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, pasha.tatashin@soleen.com, syzkaller-bugs@googlegroups.com, Andrew Donnellan Subject: Re: [syzbot] [mm?] kernel BUG in page_table_check_set In-Reply-To: <20250822181653.cd2024360870ef94cdb7db07@linux-foundation.org> Date: Sat, 23 Aug 2025 08:53:28 +0530 Message-ID: <875xeeafgv.fsf@gmail.com> References: <68a7ef20.050a0220.37038e.004d.GAE@google.com> <20250822181653.cd2024360870ef94cdb7db07@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Andrew Morton writes: > On Thu, 21 Aug 2025 21:16:32 -0700 syzbot wrote: > >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 8f5ae30d69d7 Linux 6.17-rc1 >> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci >> console output: https://syzkaller.appspot.com/x/log.txt?x=15f926f0580000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=8c5ac3d8b8abfcb >> dashboard link: https://syzkaller.appspot.com/bug?extid=49a796ed2c9709652f1e >> compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 >> userspace arch: arm64 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15faa7a2580000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=144143bc580000 >> >> Downloadable assets: >> disk image: https://storage.googleapis.com/syzbot-assets/18a2e4bd0c4a/disk-8f5ae30d.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/3b5395881b25/vmlinux-8f5ae30d.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/e875f4e3b7ff/Image-8f5ae30d.gz.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+49a796ed2c9709652f1e@syzkaller.appspotmail.com >> >> ------------[ cut here ]------------ >> kernel BUG at mm/page_table_check.c:118! > > Thanks. > > Presumably due to the series "Support page table check on PowerPC". The syzbot triggered this on: HEAD commit: 8f5ae30d69d7 Linux 6.17-rc1 git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci This tree does not have "Support page table check on PowerPC", correct? Also, I guess Dev's change fixes this reported problem which could happen in this path: commit_anon_folio_batch() -> change_pte_range() ... [1]: https://lore.kernel.org/all/20250812060124.C9344C4CEF0@smtp.kernel.org/ [2]: https://lore.kernel.org/all/68a80cc6.050a0220.3809a8.0002.GAE@google.com/ -ritesh > Andrew, could you please take a look? > > The series has been in mm.git for a week so I guess the impact of this > is small. I won't drop it at this time, but prompt attention would be > appreciated. > >> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP >> Modules linked in: >> CPU: 1 UID: 0 PID: 6740 Comm: syz.0.17 Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 >> pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) >> pc : page_table_check_set+0x584/0x590 mm/page_table_check.c:118 >> lr : page_table_check_set+0x584/0x590 mm/page_table_check.c:118 >> sp : ffff80009c9674c0 >> x29: ffff80009c9674d0 x28: ffff80008fae0000 x27: 0000000000000002 >> x26: ffff0000c079ca80 x25: 0000000000000001 x24: 0000000000000001 >> x23: ffff0000c079ca80 x22: 000000000012b950 x21: 0000000000000001 >> x20: 0000000000000003 x19: 1ffff00012eb65b0 x18: 0000000000000000 >> x17: 0000000000000000 x16: ffff800080528a28 x15: 0000000000000001 >> x14: 1fffe000180f3950 x13: 0000000000000000 x12: 0000000000000000 >> x11: ffff6000180f3951 x10: 0000000000ff0100 x9 : 0000000000000000 >> x8 : ffff0000cdb05b80 x7 : ffff800080d16554 x6 : 0000000000000000 >> x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080d15b5c >> x2 : 0000000000000001 x1 : 0000000000000002 x0 : 0000000000000001 >> Call trace: >> page_table_check_set+0x584/0x590 mm/page_table_check.c:118 (P) >> __page_table_check_ptes_set+0x2a8/0x2e0 mm/page_table_check.c:209 >> page_table_check_ptes_set include/linux/page_table_check.h:76 [inline] >> __set_ptes_anysz arch/arm64/include/asm/pgtable.h:709 [inline] >> __set_ptes+0x4a0/0x504 arch/arm64/include/asm/pgtable.h:741 >> contpte_set_ptes+0x120/0x188 arch/arm64/mm/contpte.c:464 >> set_ptes arch/arm64/include/asm/pgtable.h:1794 [inline] >> modify_prot_commit_ptes+0x4e4/0x694 arch/arm64/mm/mmu.c:1556 >> prot_commit_flush_ptes mm/mprotect.c:197 [inline] >> commit_anon_folio_batch mm/mprotect.c:246 [inline] >> set_write_prot_commit_flush_ptes mm/mprotect.c:273 [inline] >> change_pte_range mm/mprotect.c:354 [inline] >> change_pmd_range mm/mprotect.c:570 [inline] >> change_pud_range mm/mprotect.c:633 [inline] >> change_p4d_range mm/mprotect.c:659 [inline] >> change_protection_range mm/mprotect.c:687 [inline] >> change_protection+0x1e84/0x3ff0 mm/mprotect.c:721 >> mprotect_fixup+0x504/0x744 mm/mprotect.c:837 >> do_mprotect_pkey+0x864/0xb30 mm/mprotect.c:993 >> __do_sys_mprotect mm/mprotect.c:1014 [inline] >> __se_sys_mprotect mm/mprotect.c:1011 [inline] >> __arm64_sys_mprotect+0x80/0x98 mm/mprotect.c:1011 >> __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] >> invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 >> el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 >> do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 >> el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 >> 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: d4210000 97e865fd d4210000 97e865fb (d4210000) >> ---[ end trace 0000000000000000 ]--- >> >> >> --- >> 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