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Message-ID: <442A9745-DC2E-41E3-8CD6-9B5E2B55D9F3@psu.edu> Date: Tue, 14 Oct 2025 20:46:09 +0000 From: "Bai, Shuangpeng" <sjb7183@....edu> To: Chao Yu <chao@...nel.org> CC: "jaegeuk@...nel.org" <jaegeuk@...nel.org>, "linux-f2fs-devel@...ts.sourceforge.net" <linux-f2fs-devel@...ts.sourceforge.net>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "syzkaller@...glegroups.com" <syzkaller@...glegroups.com> Subject: Re: [BUG] f2fs: divide error in f2fs_all_cluster_page_ready on v6.17 > On Oct 14, 2025, at 02:18, Chao Yu <chao@...nel.org> wrote: > > On 10/14/25 01:56, Bai, Shuangpeng wrote: >> >> >>> On Oct 13, 2025, at 08:41, Chao Yu <chao@...nel.org> wrote: >>> >>> On 10/13/25 07:49, Bai, Shuangpeng wrote: >>>> Hi Kernel Maintainers, >>>> >>>> Our tool found a new kernel bug "divide error in f2fs_all_cluster_page_ready". Please see the details below. >>>> >>>> Kernel commit: 6.17 >>>> Kernel config: attachment >>>> Reproducer: attachment >>>> >>>> The reproducer triggers the crash reliably in ~500 seconds on a QEMU x86_64 VM. >>>> >>>> I’m happy to test debug patches or provide additional information. >>> >>> Hi Bai, >>> >>> Thanks for your report! >>> >>> Could you please share scripts and images for this issue? as I can not reproduce >>> w/ repro.c. >>> >> >> Thanks for your reply! >> >> I used clang-15 to compile the kernel v6.17 with the .config in the attachment. >> >> The image I used is bullseye.img (https://drive.google.com/file/d/1krL9Mc-s07aA6m-0VjuuO767StacvZQV/view?usp=share_link). >> >> The image is created by https://raw.githubusercontent.com/google/syzkaller/master/tools/create-image.sh. >> >> I will also send the boot script as attachments. >> >> This bug takes about 500 seconds to trigger the bug in our testing environment. >> >> Please let me know if anything needed. Thanks! > > Thanks for providing the information, however I still can not reproduce this bug w/ > above images and scripts. > > Could you please upload your kernel image as well? let me have a try w/ your image, > not sure it's related to clang-15 or not. > The vmlinux: https://drive.google.com/file/d/1udjEt8sSV1d_kIF3E5IZmhOThG9MDh1s/view?usp=sharing Please let me know for any further questions. Thanks, > Thanks, > >> >> >> >> >> >> >>> Thanks, >>> >>>> >>>> >>>> Oops: divide error: 0000 [#1] SMP KASAN PTI >>>> CPU: 0 UID: 0 PID: 11441 Comm: syz.0.46 Not tainted 6.17.0 #1 PREEMPT(full) >>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 >>>> RIP: 0010:f2fs_all_cluster_page_ready+0x106/0x550 fs/f2fs/compress.c:857 >>>> Code: 00 8b 4d 00 48 89 d8 48 c1 e8 20 74 19 48 89 d8 31 d2 48 f7 f1 48 89 d5 eb 14 48 89 5c 24 10 e8 40 a4 6d fd eb 2d 89 d8 31 d2 <f7> f1 89 d5 31 ff 48 89 ee e8 0c a9 6d fd 48 85 ed 74 0c e8 22 a4 >>>> RSP: 0018:ffffc90006616e60 EFLAGS: 00010246 >>>> RAX: 0000000000000003 RBX: 0000000000000003 RCX: 0000000000000000 >>>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 >>>> RBP: ffffc90006617270 R08: ffffffff84552d26 R09: 0000000000000000 >>>> R10: ffff888155ad2000 R11: ffffffff81d2aa26 R12: 0000000000000001 >>>> R13: dffffc0000000000 R14: 0000000000000010 R15: ffffc90006617260 >>>> FS: 00007f8bac5b5640(0000) GS:ffff888220f02000(0000) knlGS:0000000000000000 >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> CR2: 000056508a326000 CR3: 0000000117bec000 CR4: 00000000000006f0 >>>> Call Trace: >>>> <TASK> >>>> f2fs_write_cache_pages fs/f2fs/data.c:3078 [inline] >>>> __f2fs_write_data_pages fs/f2fs/data.c:3290 [inline] >>>> f2fs_write_data_pages+0x1c19/0x3600 fs/f2fs/data.c:3317 >>>> do_writepages+0x38e/0x640 mm/page-writeback.c:2634 >>>> filemap_fdatawrite_wbc mm/filemap.c:386 [inline] >>>> __filemap_fdatawrite_range mm/filemap.c:419 [inline] >>>> file_write_and_wait_range+0x2ba/0x3e0 mm/filemap.c:794 >>>> f2fs_do_sync_file+0x6e6/0x1b00 fs/f2fs/file.c:294 >>>> generic_write_sync include/linux/fs.h:3043 [inline] >>>> f2fs_file_write_iter+0x76e/0x2700 fs/f2fs/file.c:5259 >>>> new_sync_write fs/read_write.c:593 [inline] >>>> vfs_write+0x7e9/0xe00 fs/read_write.c:686 >>>> ksys_write+0x19d/0x2d0 fs/read_write.c:738 >>>> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] >>>> do_syscall_64+0xf7/0x470 arch/x86/entry/syscall_64.c:94 >>>> entry_SYSCALL_64_after_hwframe+0x77/0x7f >>>> RIP: 0033:0x7f8bab7ae49d >>>> Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007f8bac5b4f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >>>> RAX: ffffffffffffffda RBX: 00007f8baba26180 RCX: 00007f8bab7ae49d >>>> RDX: 000000000000ffbd RSI: 0000200000000240 RDI: 0000000000000007 >>>> RBP: 00007f8bab848268 R08: 0000000000000000 R09: 0000000000000000 >>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 >>>> R13: 00007f8baba26218 R14: 00007f8baba26180 R15: 00007f8bac595000 >>>> </TASK> >>>> Modules linked in: >>>> ---[ end trace 0000000000000000 ]--- >>>> RIP: 0010:f2fs_all_cluster_page_ready+0x106/0x550 fs/f2fs/compress.c:857 >>>> Code: 00 8b 4d 00 48 89 d8 48 c1 e8 20 74 19 48 89 d8 31 d2 48 f7 f1 48 89 d5 eb 14 48 89 5c 24 10 e8 40 a4 6d fd eb 2d 89 d8 31 d2 <f7> f1 89 d5 31 ff 48 89 ee e8 0c a9 6d fd 48 85 ed 74 0c e8 22 a4 >>>> RSP: 0018:ffffc90006616e60 EFLAGS: 00010246 >>>> RAX: 0000000000000003 RBX: 0000000000000003 RCX: 0000000000000000 >>>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 >>>> RBP: ffffc90006617270 R08: ffffffff84552d26 R09: 0000000000000000 >>>> R10: ffff888155ad2000 R11: ffffffff81d2aa26 R12: 0000000000000001 >>>> R13: dffffc0000000000 R14: 0000000000000010 R15: ffffc90006617260 >>>> FS: 00007f8bac5b5640(0000) GS:ffff888220f02000(0000) knlGS:0000000000000000 >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> CR2: 000056508a326000 CR3: 0000000117bec000 CR4: 00000000000006f0 >>>> ---------------- >>>> Code disassembly (best guess): >>>> 0: 00 8b 4d 00 48 89 add %cl,-0x76b7ffb3(%rbx) >>>> 6: d8 48 c1 fmuls -0x3f(%rax) >>>> 9: e8 20 74 19 48 call 0x4819742e >>>> e: 89 d8 mov %ebx,%eax >>>> 10: 31 d2 xor %edx,%edx >>>> 12: 48 f7 f1 div %rcx >>>> 15: 48 89 d5 mov %rdx,%rbp >>>> 18: eb 14 jmp 0x2e >>>> 1a: 48 89 5c 24 10 mov %rbx,0x10(%rsp) >>>> 1f: e8 40 a4 6d fd call 0xfd6da464 >>>> 24: eb 2d jmp 0x53 >>>> 26: 89 d8 mov %ebx,%eax >>>> 28: 31 d2 xor %edx,%edx >>>> * 2a: f7 f1 div %ecx <-- trapping instruction >>>> 2c: 89 d5 mov %edx,%ebp >>>> 2e: 31 ff xor %edi,%edi >>>> 30: 48 89 ee mov %rbp,%rsi >>>> 33: e8 0c a9 6d fd call 0xfd6da944 >>>> 38: 48 85 ed test %rbp,%rbp >>>> 3b: 74 0c je 0x49 >>>> 3d: e8 .byte 0xe8 >>>> 3e: 22 .byte 0x22 >>>> 3f: a4 movsb %ds:(%rsi),%es:(%rdi) >>>> >>>> Best, >>>> Shuangpeng
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