Hi Georges,

Thanks for v2, LGTM, ack.

Thanks,
Tao Liu

On Tue, Sep 30, 2025 at 7:14 PM Aureau, Georges (Kernel Tools ERT)
<[email protected]> wrote:
>
> [PATCH 2/v2] Fix "mount" MNT_CURSOR (kernels 5.8-6.7):
>
> Fix "mount" MNT_CURSOR entries (kernels 5.8-6.7):
>
> crash> mount > mount.out
> WARNING: cannot get super_block from vfsmnt: 0xff35d65eb1cc1820
> crash> struct mount.mnt.mnt_sb,mnt.mnt_flags -x 0xff35d65eb1cc1820
>   mnt.mnt_sb = 0x0,
>   mnt.mnt_flags = 0x10000000,
>
> When crashing with running "findmnt" commands, the mount list will
> have entries with mnt.mnt_flags==MNT_CURSOR (and mnt.mnt_sb==NULL).
> Such entries should be skipped without errors.
>
> Signed-off-by: Georges Aureau <[email protected]>
> --
>  defs.h    |  2 ++
>  filesys.c | 15 +++++++++++++++
>  symbols.c |  4 ++++
>  3 files changed, 21 insertions(+)
>
> diff --git a/defs.h b/defs.h
> index 156ac02..3fd7d89 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2274,6 +2274,8 @@ struct offset_table {                    /* stash of 
> commonly-used offsets */
>         long request_queue_tag_set;
>         long blk_mq_tag_set_flags;
>         long blk_mq_tag_set_shared_tags;
> +       long vfsmount_mnt_flags;
> +       long proc_mounts_cursor;
>  };
>
>  struct size_table {         /* stash of commonly-used sizes */
> diff --git a/filesys.c b/filesys.c
> index 8d13807..1f8803d 100644
> --- a/filesys.c
> +++ b/filesys.c
> @@ -1367,6 +1367,10 @@ cmd_mount(void)
>         close_tmpfile();
>  }
>
> +/* For kernels 5.8-6.7, we're skipping show mount cursor entries.
> + */
> +#define MNT_CURSOR             0x10000000
> +
>  /*
>   *  Do the work for cmd_mount();
>   */
> @@ -1492,6 +1496,15 @@ show_mounts(ulong one_vfsmount, int flags, struct 
> task_context *namespace_contex
>
>                 sbp = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb));
>                 if (!IS_KVADDR(sbp)) {
> +                       if (sbp == 0 && VALID_MEMBER(proc_mounts_cursor) &&
> +                           VALID_MEMBER(vfsmount_mnt_flags)) {
> +                               int mnt_flags = INT(vfsmount_buf + 
> OFFSET(vfsmount_mnt_flags));
> +                               if (mnt_flags == MNT_CURSOR) {
> +                                       if (CRASHDEBUG(1))
> +                                               fprintf(stderr,"skipped 
> cursor vfsmnt: 0x%lx\n", *vfsmnt);
> +                                       continue;
> +                               }
> +                       }
>                         error(WARNING, "cannot get super_block from vfsmnt: 
> 0x%lx\n", *vfsmnt);
>                         continue;
>                 }
> @@ -2081,6 +2094,8 @@ vfs_init(void)
>         if (INVALID_MEMBER(vfsmount_mnt_devname))
>                 MEMBER_OFFSET_INIT(mount_mnt_mountpoint,
>                         "mount", "mnt_mountpoint");
> +       MEMBER_OFFSET_INIT(vfsmount_mnt_flags, "vfsmount", "mnt_flags");
> +       MEMBER_OFFSET_INIT(proc_mounts_cursor, "proc_mounts", "cursor");
>         MEMBER_OFFSET_INIT(mount_mnt, "mount", "mnt");
>         MEMBER_OFFSET_INIT(namespace_root, "namespace", "root");
>         MEMBER_OFFSET_INIT(task_struct_nsproxy, "task_struct", "nsproxy");
> diff --git a/symbols.c b/symbols.c
> index 112bcc6..fd91c2e 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -10691,6 +10691,10 @@ dump_offset_table(char *spec, ulong makestruct)
>                 OFFSET(vfsmount_mnt_mountpoint));
>          fprintf(fp, "           vfsmount_mnt_parent: %ld\n",
>                 OFFSET(vfsmount_mnt_parent));
> +        fprintf(fp, "            vfsmount_mnt_flags: %ld\n",
> +               OFFSET(vfsmount_mnt_flags));
> +        fprintf(fp, "            proc_mounts_cursor: %ld\n",
> +               OFFSET(proc_mounts_cursor));
>         fprintf(fp, "              mount_mnt_parent: %ld\n",
>                 OFFSET(mount_mnt_parent));
>         fprintf(fp, "          mount_mnt_mountpoint: %ld\n",
> --
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