[Crash-utility] Re: [PATCH] Fix "mount" command failure on Linux 6.8-rc1 and later

Kernel commit 2eea9ce4310d ("mounts: keep list of mounts in an rbtree") changed the structure that keeps the list of mounts to an rbtree. Without the patch, "mount" command fails with the following error: crash> mount mount: invalid structure member offset: mnt_namespace_list FILE: filesys.c LINE: 1643 FUNCTION: get_mount_list()

Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; --- defs.h | 3 +++ filesys.c | 29 +++++++++++++++++++++++++++++ symbols.c | 3 +++ 3 files changed, 35 insertions(+) diff --git a/defs.h b/defs.h index d1edce9893d1..ca1ac79ffa3e 100644 --- a/defs.h +++ b/defs.h @@ -2236,6 +2236,9 @@ struct offset_table { /* stash of commonly-used offsets */ long zram_comp_algs; long task_struct_thread_reg01; long task_struct_thread_reg03; + long mnt_namespace_mounts; + long mnt_namespace_nr_mounts; + long mount_mnt_node; }; struct size_table { /* stash of commonly-used sizes */ diff --git a/filesys.c b/filesys.c index 1d0ee7f0b24a..81fe856699e1 100644 --- a/filesys.c +++ b/filesys.c @@ -1634,6 +1634,31 @@ get_mount_list(int *cntptr, struct task_context *namespace_context) &mnt_ns, sizeof(void *), "nsproxy mnt_ns", RETURN_ON_ERROR|QUIET)) error(FATAL, "cannot determine mount list location!\n"); + + /* Linux 6.8 and later keep list of mounts in an rbtree. */ + if (VALID_MEMBER(mnt_namespace_nr_mounts)) { + uint nr_mounts; + ulong *mntlist, *l; + struct rb_root *mounts; + struct rb_node *node; + + readmem(mnt_ns + OFFSET(mnt_namespace_nr_mounts), KVADDR, &nr_mounts, + sizeof(uint), "mnt_namespace.nr_mounts", FAULT_ON_ERROR); + + if (!nr_mounts) + error(FATAL, "nr_mounts is zero!\n"); + + mounts = (struct rb_root *)(mnt_ns + OFFSET(mnt_namespace_mounts)); + + mntlist = (ulong *)GETBUF(sizeof(ulong) * nr_mounts); + l = mntlist; + for (node = rb_first(mounts); node; l++, node = rb_next(node)) + *l = (ulong)node - OFFSET(mount_mnt_node); + + *cntptr = nr_mounts; + return mntlist; + } + if (!readmem(mnt_ns + OFFSET(mnt_namespace_root), KVADDR, &root, sizeof(void *), "mnt_namespace root", RETURN_ON_ERROR|QUIET)) @@ -2063,6 +2088,10 @@ vfs_init(void) MEMBER_OFFSET_INIT(nsproxy_mnt_ns, "nsproxy", "mnt_ns"); MEMBER_OFFSET_INIT(mnt_namespace_root, "mnt_namespace", "root"); MEMBER_OFFSET_INIT(mnt_namespace_list, "mnt_namespace", "list"); + /* Linux 6.8 and later */ + MEMBER_OFFSET_INIT(mnt_namespace_mounts, "mnt_namespace", "mounts"); + MEMBER_OFFSET_INIT(mnt_namespace_nr_mounts, "mnt_namespace", "nr_mounts"); + MEMBER_OFFSET_INIT(mount_mnt_node, "mount", "mnt_node"); } else if (THIS_KERNEL_VERSION >= LINUX(2,4,20)) { if (CRASHDEBUG(2)) fprintf(fp, "hardwiring namespace stuff\n"); diff --git a/symbols.c b/symbols.c index d43785d3126a..b07b101767c8 100644 --- a/symbols.c +++ b/symbols.c @@ -9925,6 +9925,8 @@ dump_offset_table(char *spec, ulong makestruct) OFFSET(mnt_namespace_root)); fprintf(fp, " mnt_namespace_list: %ld\n", OFFSET(mnt_namespace_list)); + fprintf(fp, " mnt_namespace_mounts: %ld\n", OFFSET(mnt_namespace_mounts)); + fprintf(fp, " mnt_namespace_nr_mounts: %ld\n", OFFSET(mnt_namespace_nr_mounts)); fprintf(fp, " pid_namespace_idr: %ld\n", OFFSET(pid_namespace_idr)); @@ -10581,6 +10583,7 @@ dump_offset_table(char *spec, ulong makestruct) OFFSET(mount_mnt_devname)); fprintf(fp, " mount_mnt: %ld\n", OFFSET(mount_mnt)); + fprintf(fp, " mount_mnt_node: %ld\n", OFFSET(mount_mnt_node)); fprintf(fp, " namespace_root: %ld\n", OFFSET(namespace_root)); fprintf(fp, " namespace_list: %ld\n",