Re: a deadloop(?) when mkfs.xfs -o rtdev

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

> There seems a deadloop(?) when mkfs.xfs -o rtdev.
> 
> # mkfs.xfs -r rtdev=/dev/disk/by-id/ata-MZ7KM1T6HAJM00D3_S2CXNAAH600026 /dev/d
> isk/by-id/scsi-SHITACHI_HUSMH842_CLAR100_0LX0JWVA -f
> meta-data=/dev/disk/by-id/scsi-SHITACHI_HUSMH842_CLAR100_0LX0JWVA isize=512    agcount=20, agsize=1221072 blks
>          =                       sectsz=4096  attr=2, projid32bit=1
>          =                       crc=1        finobt=1, sparse=1, rmapbt=0
>          =                       reflink=0    bigtime=1 inobtcount=1 nrext64=1
>          =                       exchange=0
> data     =                       bsize=4096   blocks=24421440, imaxpct=25
>          =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096   ascii-ci=0, ftype=1, parent=0
> log      =internal log           bsize=4096   blocks=41799, version=2
>          =                       sectsz=4096  sunit=1 blks, lazy-count=1
> realtime =/dev/disk/by-id/ata-MZ7KM1T6HAJM00D3_S2CXNAAH600026 extsz=4096   blocks=390703446, rtextents=390703446
> Discarding blocks...Done.
> Discarding blocks...Done.
> 
> It did not fishish after 10 mins.
> 
> # pstack 5785
> #0  0x00007f8df5efc01a in pread64 () from /lib64/libc.so.6
> #1  0x0000557b7bbfe9c3 in __read_buf.constprop.0 ()
> #2  0x0000557b7bbc3030 in libxfs_buf_read_map ()
> #3  0x0000557b7bbfe1ae in libxfs_trans_read_buf_map.constprop ()
> #4  0x0000557b7bbee7ef in xfs_rtbuf_get ()
> #5  0x0000557b7bbf03d8 in libxfs_rtfree_extent ()
> #6  0x0000557b7bbbb322 in parseproto.lto_priv ()
> #7  0x0000557b7bbb7643 in main ()
> 
> And,
> 1) more chance happen when kernel 6.12.36, but yet not happen when kernel 6.6.93.
> 2) it happen on both xfsprogs-6.11.0 and xfsprogs-6.4.

it happen on xfsprogs-6.15.0 too.

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2025/07/17