[Bug 263765] panic: ffs_sync: modification on read-only filesystem
Date: Wed, 04 May 2022 00:44:28 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=263765 Bug ID: 263765 Summary: panic: ffs_sync: modification on read-only filesystem Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: markj@FreeBSD.org I was using a VM to test some code and crashed it many times. After a while it consistently panics during boot, while upgrading the read-only root mount to read-write: Trying to mount root from ufs:gpt/rootfs [rw]... WARNING: / was not properly dismounted WARNING: /: mount pending error: blocks 367136 files 5 No suitable dump device was found. Setting hostuuid: 4ff7a735-851c-7030-87f0-cf2c2b9ef44e. Setting hostid: 0x1c981ebb. Starting file system checks: WARNING: / was not properly dismounted panic: /: ffs_sync: modification on read-only filesystem cpuid = 1 time = 1651623448 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe007a140750 vpanic() at vpanic+0x17f/frame 0xfffffe007a1407a0 panic() at panic+0x43/frame 0xfffffe007a140800 ffs_sync() at ffs_sync+0x6e6/frame 0xfffffe007a1408a0 vfs_write_suspend() at vfs_write_suspend+0x165/frame 0xfffffe007a1408f0 vfs_write_suspend_umnt() at vfs_write_suspend_umnt+0x35/frame 0xfffffe007a140920 ffs_mount() at ffs_mount+0xa2b/frame 0xfffffe007a140a70 vfs_domount_update() at vfs_domount_update+0x277/frame 0xfffffe007a140bf0 vfs_domount() at vfs_domount+0x26b/frame 0xfffffe007a140d20 vfs_donmount() at vfs_donmount+0x878/frame 0xfffffe007a140dc0 sys_nmount() at sys_nmount+0x69/frame 0xfffffe007a140e00 amd64_syscall() at amd64_syscall+0x12e/frame 0xfffffe007a140f30 fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe007a140f30 --- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x28658b33e3da, rsp = 0x286588ae7e38, rbp = 0x286588ae83a0 --- The problem appears to be that the fmod flag in the superblock got set, somehow: magic 19540119 (UFS2) last mounted time Mon May 2 21:00:40 2022 last modified time Mon May 2 21:00:52 2022 superblock location 65536 id [ 62658b45 0a5e546e ] ncg 82 size 13107200 blocks 12694551 bsize 32768 shift 15 mask 0xffff8000 fsize 4096 shift 12 mask 0xfffff000 frag 8 shift 3 fsbtodb 3 minfree 8% optim time symlinklen 120 maxbsize 32768 maxbpg 8192 maxcontig 2 contigsumsize 2 nbfree 1377660 ndir 4007 nifree 6527315 nffree 6053 bpg 20042 fpg 160336 ipg 80256 unrefs 0 nindir 4096 inopb 128 maxfilesize 2252349704110079 sbsize 4096 cgsize 32768 csaddr 5056 cssize 4096 sblkno 24 cblkno 32 iblkno 40 dblkno 5056 cgrotor 7 fmod 1 ronly 0 clean 0 metaspace 0 avgfpdir 64 avgfilesize 16384 flags unclean soft-updates Running fsck from single-user mode fixed the problem, but it reappeared several times. I'm not really sure how fmod can end up set; it looks like it's cleared any time FFS updates the superblock. (But then why is it in the superblock at all?) I don't appear to have checksums enabled here, maybe enabling them would help narrow down the problem. -- You are receiving this mail because: You are the assignee for the bug.