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List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:b49:b0:425:7524:8b38 with SMTP id e9e14a558f8ab-4259562c487mr100691175ab.22.1759231015795; Tue, 30 Sep 2025 04:16:55 -0700 (PDT) Date: Tue, 30 Sep 2025 04:16:55 -0700 In-Reply-To: <20250930071053.36158-1-lance.yang@linux.dev> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68dbbc27.a00a0220.102ee.0047.GAE@google.com> Subject: [syzbot ci] Re: mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage From: syzbot ci To: akpm@linux-foundation.org, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, david@redhat.com, dev.jain@arm.com, gourry@gourry.net, harry.yoo@oracle.com, ioworker0@gmail.com, jannh@google.com, joshua.hahnjy@gmail.com, lance.yang@linux.dev, liam.howlett@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, npache@redhat.com, peterx@redhat.com, rakie.kim@sk.com, riel@surriel.com, ryan.roberts@arm.com, stable@vger.kernel.org, usamaarif642@gmail.com, vbabka@suse.cz, ying.huang@linux.alibaba.com, yuzhao@google.com, ziy@nvidia.com Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v4] mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage https://lore.kernel.org/all/20250930071053.36158-1-lance.yang@linux.dev * [PATCH v4 1/1] mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage and found the following issue: general protection fault in remove_migration_pte Full report is available here: https://ci.syzbot.org/series/8cc7e52f-a859-4251-bd08-9787cdaf7928 *** general protection fault in remove_migration_pte tree: linux-next URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next base: 262858079afde6d367ce3db183c74d8a43a0e83f arch: amd64 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 config: https://ci.syzbot.org/builds/97ee4826-5d29-472d-a85d-51543b0e45de/config C repro: https://ci.syzbot.org/findings/f4819db2-21f2-4280-8bc4-942445398953/c_repro syz repro: https://ci.syzbot.org/findings/f4819db2-21f2-4280-8bc4-942445398953/syz_repro Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 UID: 0 PID: 6025 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:ptep_get include/linux/pgtable.h:340 [inline] RIP: 0010:remove_migration_pte+0x369/0x2320 mm/migrate.c:352 Code: 00 48 8d 43 20 48 89 44 24 68 49 8d 47 40 48 89 84 24 e8 00 00 00 4c 89 64 24 48 4c 8b b4 24 50 01 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 f8 3e ff ff 49 8b 06 48 89 44 24 RSP: 0018:ffffc90002fb73e0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88802957e300 RCX: 1ffffd40008c9006 RDX: 0000000000000000 RSI: 0000000000030dff RDI: 0000000000030c00 RBP: ffffc90002fb75d0 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520005f6e34 R12: ffffea0004648008 R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0004648000 FS: 00005555624de500(0000) GS:ffff8880b83fc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000300 CR3: 000000010d8b8000 CR4: 00000000000006f0 Call Trace: rmap_walk_anon+0x553/0x730 mm/rmap.c:2855 remove_migration_ptes mm/migrate.c:469 [inline] migrate_folio_move mm/migrate.c:1381 [inline] migrate_folios_move mm/migrate.c:1711 [inline] migrate_pages_batch+0x202e/0x35e0 mm/migrate.c:1967 migrate_pages_sync mm/migrate.c:1997 [inline] migrate_pages+0x1bcc/0x2930 mm/migrate.c:2106 migrate_to_node mm/mempolicy.c:1244 [inline] do_migrate_pages+0x5ee/0x800 mm/mempolicy.c:1343 kernel_migrate_pages mm/mempolicy.c:1858 [inline] __do_sys_migrate_pages mm/mempolicy.c:1876 [inline] __se_sys_migrate_pages+0x544/0x650 mm/mempolicy.c:1872 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb18e18ec29 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdca5c9838 EFLAGS: 00000246 ORIG_RAX: 0000000000000100 RAX: ffffffffffffffda RBX: 00007fb18e3d5fa0 RCX: 00007fb18e18ec29 RDX: 0000200000000300 RSI: 0000000000000003 RDI: 0000000000000000 RBP: 00007fb18e211e41 R08: 0000000000000000 R09: 0000000000000000 R10: 0000200000000040 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb18e3d5fa0 R14: 00007fb18e3d5fa0 R15: 0000000000000004 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:ptep_get include/linux/pgtable.h:340 [inline] RIP: 0010:remove_migration_pte+0x369/0x2320 mm/migrate.c:352 Code: 00 48 8d 43 20 48 89 44 24 68 49 8d 47 40 48 89 84 24 e8 00 00 00 4c 89 64 24 48 4c 8b b4 24 50 01 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 f8 3e ff ff 49 8b 06 48 89 44 24 RSP: 0018:ffffc90002fb73e0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88802957e300 RCX: 1ffffd40008c9006 RDX: 0000000000000000 RSI: 0000000000030dff RDI: 0000000000030c00 RBP: ffffc90002fb75d0 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520005f6e34 R12: ffffea0004648008 R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0004648000 FS: 00005555624de500(0000) GS:ffff8880b83fc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000300 CR3: 000000010d8b8000 CR4: 00000000000006f0 ---------------- Code disassembly (best guess): 0: 00 48 8d add %cl,-0x73(%rax) 3: 43 20 48 89 rex.XB and %cl,-0x77(%r8) 7: 44 24 68 rex.R and $0x68,%al a: 49 8d 47 40 lea 0x40(%r15),%rax e: 48 89 84 24 e8 00 00 mov %rax,0xe8(%rsp) 15: 00 16: 4c 89 64 24 48 mov %r12,0x48(%rsp) 1b: 4c 8b b4 24 50 01 00 mov 0x150(%rsp),%r14 22: 00 23: 4c 89 f0 mov %r14,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 4c 89 f7 mov %r14,%rdi 34: e8 f8 3e ff ff call 0xffff3f31 39: 49 8b 06 mov (%r14),%rax 3c: 48 rex.W 3d: 89 .byte 0x89 3e: 44 rex.R 3f: 24 .byte 0x24 *** 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.