diff --git a/src/analyze/analyze-filesystems.c b/src/analyze/analyze-filesystems.c
index 582e04eac91..b09cd9fa0ee 100644
--- a/src/analyze/analyze-filesystems.c
+++ b/src/analyze/analyze-filesystems.c
@@ -17,7 +17,7 @@ static int load_available_kernel_filesystems(Set **ret) {
 
         /* Let's read the available filesystems */
 
-        r = read_virtual_file("/proc/filesystems", SIZE_MAX, &t, NULL);
+        r = read_full_file("/proc/filesystems", &t, /* ret_size= */ NULL);
         if (r < 0)
                 return r;
 
diff --git a/src/basic/fileio.c b/src/basic/fileio.c
index 25b4c352355..b3fdc05c127 100644
--- a/src/basic/fileio.c
+++ b/src/basic/fileio.c
@@ -491,7 +491,11 @@ int read_virtual_file_at(
          * max_size specifies a limit on the bytes read. If max_size is SIZE_MAX, the full file is read. If
          * the full file is too large to read, an error is returned. For other values of max_size, *partial
          * contents* may be returned. (Though the read is still done using one syscall.) Returns 0 on
-         * partial success, 1 if untruncated contents were read. */
+         * partial success, 1 if untruncated contents were read.
+         *
+         * Rule: for kernfs files using "seq_file" → use regular read_full_file_at()
+         *       for kernfs files using "raw" → use read_virtual_file_at()
+         */
 
         assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
         assert(max_size <= READ_VIRTUAL_BYTES_MAX || max_size == SIZE_MAX);
diff --git a/src/basic/proc-cmdline.c b/src/basic/proc-cmdline.c
index 93d2d0e2026..7f8e32f6795 100644
--- a/src/basic/proc-cmdline.c
+++ b/src/basic/proc-cmdline.c
@@ -122,7 +122,7 @@ int proc_cmdline(char **ret) {
         if (detect_container() > 0)
                 return pid_get_cmdline(1, SIZE_MAX, 0, ret);
 
-        return read_virtual_file("/proc/cmdline", SIZE_MAX, ret, NULL);
+        return read_full_file("/proc/cmdline", ret, /* ret_size= */  NULL);
 }
 
 static int proc_cmdline_strv_internal(char ***ret, bool filter_pid1_args) {
diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index 21fb48a9ac7..03690a0837b 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -1399,28 +1399,28 @@ static int gather_pid_metadata_from_procfs(struct iovec_wrapper *iovw, Context *
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_OPEN_FDS=", t);
 
         p = procfs_file_alloca(pid, "status");
-        if (read_full_virtual_file(p, &t, NULL) >= 0)
+        if (read_full_file(p, &t, /* ret_size= */ NULL) >= 0)
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_PROC_STATUS=", t);
 
         p = procfs_file_alloca(pid, "maps");
-        if (read_full_virtual_file(p, &t, NULL) >= 0)
+        if (read_full_file(p, &t, /* ret_size= */ NULL) >= 0)
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_PROC_MAPS=", t);
 
-        p = procfs_file_alloca(pid, "limits");
-        if (read_full_virtual_file(p, &t, NULL) >= 0)
+        p = procfs_file_alloca(pid, "limits"); /* this uses 'seq_file' in kernel, use read_full_file_at() */
+        if (read_full_file(p, &t, /* ret_size= */ NULL) >= 0)
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_PROC_LIMITS=", t);
 
         p = procfs_file_alloca(pid, "cgroup");
-        if (read_full_virtual_file(p, &t, NULL) >= 0)
+        if (read_full_file(p, &t, /* ret_size= */ NULL) >= 0)
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_PROC_CGROUP=", t);
 
         p = procfs_file_alloca(pid, "mountinfo");
-        if (read_full_virtual_file(p, &t, NULL) >= 0)
+        if (read_full_file(p, &t, /* ret_size= */ NULL) >= 0)
                 (void) iovw_put_string_field_free(iovw, "COREDUMP_PROC_MOUNTINFO=", t);
 
         /* We attach /proc/auxv here. ELF coredumps also contain a note for this (NT_AUXV), see elf(5). */
         p = procfs_file_alloca(pid, "auxv");
-        if (read_full_virtual_file(p, &t, &size) >= 0) {
+        if (read_full_file(p, &t, &size) >= 0) {
                 char *buf = malloc(strlen("COREDUMP_PROC_AUXV=") + size + 1);
                 if (buf) {
                         /* Add a dummy terminator to make context_parse_iovw() happy. */