Re: [Crash-utility] [PATCH] Fix mount command to appropriately display the mount dumps
On 2022/12/20 12:16, Lianbo Jiang wrote:
Recently the following failure has been observed on some vmcores
when
using the mount command:
crash> mount
MOUNT SUPERBLK TYPE DEVNAME DIRNAME
ffff97a4818a3480 ffff979500013800 rootfs none /
ffff97e4846ca700 ffff97e484653000 sysfs sysfs /sys
...
ffff97b484753420 0 mount: invalid kernel virtual address: 0 type:
"super_block buffer"
Thank you for the fix.
Just out of curiosity, do you see why the vfsmount.mnt_sb is zero?
That panic occurred during mounting or unmounting?
Thanks,
Kazu
>
> The kernel virtual address of the super_block is zero when the mount
> command fails at the address 0xffff97b484753420. And the remaining
> dumping information will be discarded. That is not expected.
>
> Check the address and skip it, if this is an invalid kernel virtual
> address, that can avoid truncating the remaining mount dumps.
>
> Reported-by: Dave Wysochanski <dwysocha(a)redhat.com>
> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com>
> ---
> filesys.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/filesys.c b/filesys.c
> index c2ea78de821d..8c2d4e316208 100644
> --- a/filesys.c
> +++ b/filesys.c
> @@ -1491,6 +1491,8 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context
*namespace_contex
> }
>
> sbp = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb));
> + if (!IS_KVADDR(sbp))
> + continue;
>
> if (flags)
> fprintf(fp, "%s", mount_hdr);