* Re: [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments [not found] <69b8c9a9.a00a0220.3b25d1.002a.GAE@google.com> @ 2026-03-23 0:49 ` syzbot 2026-03-24 10:45 ` Junjie Cao 0 siblings, 1 reply; 4+ messages in thread From: syzbot @ 2026-03-23 0:49 UTC (permalink / raw) To: junjie.cao, konishi.ryusuke, linux-kernel, linux-nilfs, slava, stable, syzkaller-bugs syzbot has found a reproducer for the following issue on: HEAD commit: 785f0eb2f85d Add linux-next specific files for 20260320 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10d95e02580000 kernel config: https://syzkaller.appspot.com/x/.config?x=c584910d0d74158d dashboard link: https://syzkaller.appspot.com/bug?extid=466a45fcfb0562f5b9a0 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=14a941d6580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14d95e02580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/a1f7fd9c1a63/disk-785f0eb2.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/6c138da87c25/vmlinux-785f0eb2.xz kernel image: https://storage.googleapis.com/syzbot-assets/4d1be64e56db/bzImage-785f0eb2.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/35af4078ce5c/mount_0.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+466a45fcfb0562f5b9a0@syzkaller.appspotmail.com loop0: detected capacity change from 0 to 4096 ------------[ cut here ]------------ ret == -ENOENT WARNING: fs/nilfs2/ioctl.c:757 at nilfs_ioctl_mark_blocks_dirty fs/nilfs2/ioctl.c:757 [inline], CPU#1: syz.0.17/6067 WARNING: fs/nilfs2/ioctl.c:757 at nilfs_ioctl_prepare_clean_segments+0x7e7/0x800 fs/nilfs2/ioctl.c:799, CPU#1: syz.0.17/6067 Modules linked in: CPU: 1 UID: 0 PID: 6067 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:nilfs_ioctl_mark_blocks_dirty fs/nilfs2/ioctl.c:757 [inline] RIP: 0010:nilfs_ioctl_prepare_clean_segments+0x7e7/0x800 fs/nilfs2/ioctl.c:799 Code: fe e9 3e fa ff ff 44 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d4 fa ff ff 4c 89 ef e8 34 a7 7e fe e9 c7 fa ff ff e8 fa 40 15 fe 90 <0f> 0b 90 41 bf fe ff ff ff e9 e3 fe ff ff 66 66 2e 0f 1f 84 00 00 RSP: 0018:ffffc90002f17640 EFLAGS: 00010293 RAX: ffffffff83b11086 RBX: 00000000fffffffe RCX: ffff888029a05b80 RDX: 0000000000000000 RSI: ffffffff8ecbc490 RDI: 00000000fffffffe RBP: ffffc90002f17730 R08: ffff888029a05b80 R09: 0000000000000002 R10: 00000000fffffffe R11: 0000000000000000 R12: dffffc0000000000 R13: 0000000000000020 R14: ffff88805c254560 R15: ffff88807ade9180 FS: 0000555588d41500(0000) GS:ffff888125548000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b31063fff CR3: 0000000078882000 CR4: 00000000003526f0 Call Trace: <TASK> nilfs_clean_segments+0x18c/0xa50 fs/nilfs2/segment.c:2525 nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:916 [inline] nilfs_ioctl+0x261f/0x2780 fs/nilfs2/ioctl.c:1346 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 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: 0033:0x7f2426b9c799 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:00007ffcedafafd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f2426e15fa0 RCX: 00007f2426b9c799 RDX: 0000200000000000 RSI: 0000000040786e88 RDI: 0000000000000004 RBP: 00007f2426c32c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2426e15fac R14: 00007f2426e15fa0 R15: 00007f2426e15fa0 </TASK> --- 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. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments 2026-03-23 0:49 ` [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments syzbot @ 2026-03-24 10:45 ` Junjie Cao 2026-03-24 11:26 ` Junjie Cao 0 siblings, 1 reply; 4+ messages in thread From: Junjie Cao @ 2026-03-24 10:45 UTC (permalink / raw) To: syzbot+466a45fcfb0562f5b9a0, Ryusuke Konishi, Viacheslav Dubeyko, linux-nilfs, linux-kernel Cc: stable, syzkaller-bugs, Junjie Cao Please test the following patch. From: Junjie Cao <junjie.cao@linux.dev> Date: Thu, 19 Mar 2026 00:00:00 +0800 Subject: [PATCH] nilfs2: skip blocks with no bmap entry in nilfs_ioctl_mark_blocks_dirty() In nilfs_ioctl_mark_blocks_dirty(), called during garbage collection, nilfs_bmap_lookup_at_level() may return -ENOENT when a block no longer exists in the DAT bmap. In that case the code sets bd_blocknr to 0 but falls through to the liveness check that compares bd_blocknr against bd_oblocknr. If bd_oblocknr also happens to be 0, the descriptor is incorrectly treated as live and the code attempts to get or mark the non-existent block, triggering a WARN_ON. Fix this by adding a continue statement so that a block descriptor is immediately skipped when its bmap lookup returns -ENOENT, since there is no block in the DAT to mark dirty. Fixes: 7942b919f732 ("nilfs2: ioctl operations") Reported-by: syzbot+466a45fcfb0562f5b9a0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=466a45fcfb0562f5b9a0 Cc: stable@vger.kernel.org Signed-off-by: Junjie Cao <junjie.cao@linux.dev> --- fs/nilfs2/ioctl.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c index 1bfe8a2..d71a0a5 100644 --- a/fs/nilfs2/ioctl.c +++ b/fs/nilfs2/ioctl.c @@ -744,6 +744,7 @@ static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs, if (ret < 0) { if (ret != -ENOENT) return ret; bdescs[i].bd_blocknr = 0; + continue; } if (bdescs[i].bd_blocknr != bdescs[i].bd_oblocknr) /* skip dead block */ -- 2.43.0 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments 2026-03-24 10:45 ` Junjie Cao @ 2026-03-24 11:26 ` Junjie Cao 2026-03-24 12:01 ` syzbot 0 siblings, 1 reply; 4+ messages in thread From: Junjie Cao @ 2026-03-24 11:26 UTC (permalink / raw) To: syzbot+466a45fcfb0562f5b9a0, Ryusuke Konishi, Viacheslav Dubeyko, linux-nilfs, linux-kernel Cc: stable, syzkaller-bugs, Junjie Cao Please test this branch. #syz test: https://github.com/Lukaaa525/linux-kernel.git nilfs2-mark-blocks-dirty-fix-syztest ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments 2026-03-24 11:26 ` Junjie Cao @ 2026-03-24 12:01 ` syzbot 0 siblings, 0 replies; 4+ messages in thread From: syzbot @ 2026-03-24 12:01 UTC (permalink / raw) To: junjie.cao, konishi.ryusuke, linux-kernel, linux-nilfs, slava, stable, syzkaller-bugs Hello, syzbot has tested the proposed patch and the reproducer did not trigger any issue: Reported-by: syzbot+466a45fcfb0562f5b9a0@syzkaller.appspotmail.com Tested-by: syzbot+466a45fcfb0562f5b9a0@syzkaller.appspotmail.com Tested on: commit: ebd34541 nilfs2: skip blocks with no bmap entry in nil.. git tree: https://github.com/Lukaaa525/linux-kernel.git nilfs2-mark-blocks-dirty-fix-syztest console output: https://syzkaller.appspot.com/x/log.txt?x=1100d6da580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a1eff8566a28238e dashboard link: https://syzkaller.appspot.com/bug?extid=466a45fcfb0562f5b9a0 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Note: no patches were applied. Note: testing is done by a robot and is best-effort only. ^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-03-23 0:49 ` [syzbot] [nilfs?] WARNING in nilfs_ioctl_prepare_clean_segments syzbot
2026-03-24 10:45 ` Junjie Cao
2026-03-24 11:26 ` Junjie Cao
2026-03-24 12:01 ` syzbot
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