tools/cgroup/slabinfo: update to work with struct slab

After the introduction of the dedicated struct slab to describe slab pages by commit d122019 ("mm: Split slab into its own type") and the following removal of the corresponding struct page's fields by commit 07f910f ("mm: Remove slab from struct page") the memcg_slabinfo tool broke. An attempt to run it produces a trace like this: Traceback (most recent call last): File "/usr/bin/drgn", line 33, in <module> sys.exit(load_entry_point('drgn==0.0.16', 'console_scripts', 'drgn')()) File "/usr/lib64/python3.9/site-packages/drgn/internal/cli.py", line 133, in main runpy.run_path(args.script[0], init_globals=init_globals, run_name="__main__") File "/usr/lib64/python3.9/runpy.py", line 268, in run_path return _run_module_code(code, init_globals, run_name, File "/usr/lib64/python3.9/runpy.py", line 97, in _run_module_code _run_code(code, mod_globals, init_globals, File "/usr/lib64/python3.9/runpy.py", line 87, in _run_code exec(code, run_globals) File "memcg_slabinfo.py", line 226, in <module> main() File "memcg_slabinfo.py", line 199, in main cache = page.slab_cache AttributeError: 'struct page' has no member 'slab_cache' The problem can be fixed by explicitly casting struct page * to struct slab * for slab pages. The tools works as expected with this fix, e.g.: cred_jar 776 776 192 21 1 : tunables 0 0 0 : slabdata 547 547 0 kmalloc-cg-32 6 6 32 128 1 : tunables 0 0 0 : slabdata 9 9 0 files_cache 3 3 832 39 8 : tunables 0 0 0 : slabdata 8 8 0 kmalloc-cg-512 1 1 512 32 4 : tunables 0 0 0 : slabdata 10 10 0 task_struct 10 10 6720 4 8 : tunables 0 0 0 : slabdata 63 63 0 mm_struct 3 3 1664 19 8 : tunables 0 0 0 : slabdata 9 9 0 kmalloc-cg-16 1 1 16 256 1 : tunables 0 0 0 : slabdata 8 8 0 pde_opener 1 1 40 102 1 : tunables 0 0 0 : slabdata 8 8 0 anon_vma_chain 375 375 64 64 1 : tunables 0 0 0 : slabdata 81 81 0 radix_tree_node 3 3 584 28 4 : tunables 0 0 0 : slabdata 419 419 0 dentry 98 98 312 26 2 : tunables 0 0 0 : slabdata 1420 1420 0 btrfs_inode 3 3 2368 13 8 : tunables 0 0 0 : slabdata 730 730 0 signal_cache 3 3 1600 20 8 : tunables 0 0 0 : slabdata 17 17 0 sighand_cache 3 3 2240 14 8 : tunables 0 0 0 : slabdata 20 20 0 filp 90 90 512 32 4 : tunables 0 0 0 : slabdata 95 95 0 anon_vma 214 214 200 20 1 : tunables 0 0 0 : slabdata 162 162 0 kmalloc-cg-1k 1 1 1024 32 8 : tunables 0 0 0 : slabdata 22 22 0 pid 10 10 256 32 2 : tunables 0 0 0 : slabdata 14 14 0 kmalloc-cg-64 2 2 64 64 1 : tunables 0 0 0 : slabdata 8 8 0 kmalloc-cg-96 3 3 96 42 1 : tunables 0 0 0 : slabdata 8 8 0 sock_inode_cache 5 5 1408 23 8 : tunables 0 0 0 : slabdata 29 29 0 UNIX 7 7 1920 17 8 : tunables 0 0 0 : slabdata 21 21 0 inode_cache 36 36 1152 28 8 : tunables 0 0 0 : slabdata 680 680 0 proc_inode_cache 26 26 1224 26 8 : tunables 0 0 0 : slabdata 64 64 0 kmalloc-cg-2k 2 2 2048 16 8 : tunables 0 0 0 : slabdata 9 9 0 v2: change naming and count_partial()/count_free()/for_each_slab() signatures to work with slabs, suggested by Matthew Wilcox Fixes: 07f910f ("mm: Remove slab from struct page") Reported-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Roman Gushchin <guro@fb.com> Tested-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Link: https://lore.kernel.org/linux-patches/Yg2cKKnIboNu7j+p@carbon.DHCP.thefacebook.com/
torvalds · Feb 21, 2022 · 2219447 · 2219447
1 parent 93dd04a
commit 2219447
Showing 1 changed file with 15 additions and 15 deletions.
diff --git a/tools/cgroup/memcg_slabinfo.py b/tools/cgroup/memcg_slabinfo.py
@@ -11,7 +11,7 @@
 from drgn.helpers.linux import for_each_page
 from drgn.helpers.linux.cpumask import for_each_online_cpu
 from drgn.helpers.linux.percpu import per_cpu_ptr
-from drgn import container_of, FaultError, Object
+from drgn import container_of, FaultError, Object, cast
 
 
 DESC = """
@@ -69,15 +69,15 @@ def oo_objects(s):
 
 
 def count_partial(n, fn):
-    nr_pages = 0
-    for page in list_for_each_entry('struct page', n.partial.address_of_(),
-                                    'lru'):
-         nr_pages += fn(page)
-    return nr_pages
+    nr_objs = 0
+    for slab in list_for_each_entry('struct slab', n.partial.address_of_(),
+                                    'slab_list'):
+         nr_objs += fn(slab)
+    return nr_objs
 
 
-def count_free(page):
-    return page.objects - page.inuse
+def count_free(slab):
+    return slab.objects - slab.inuse
 
 
 def slub_get_slabinfo(s, cfg):
@@ -145,14 +145,14 @@ def detect_kernel_config():
     return cfg
 
 
-def for_each_slab_page(prog):
+def for_each_slab(prog):
     PGSlab = 1 << prog.constant('PG_slab')
     PGHead = 1 << prog.constant('PG_head')
 
     for page in for_each_page(prog):
         try:
             if page.flags.value_() & PGSlab:
-                yield page
+                yield cast('struct slab *', page)
         except FaultError:
             pass
 
@@ -190,13 +190,13 @@ def main():
                                        'list'):
             obj_cgroups.add(ptr.value_())
 
-        # look over all slab pages, belonging to non-root memcgs
-        # and look for objects belonging to the given memory cgroup
-        for page in for_each_slab_page(prog):
-            objcg_vec_raw = page.memcg_data.value_()
+        # look over all slab folios and look for objects belonging
+        # to the given memory cgroup
+        for slab in for_each_slab(prog):
+            objcg_vec_raw = slab.memcg_data.value_()
             if objcg_vec_raw == 0:
                 continue
-            cache = page.slab_cache
+            cache = slab.slab_cache
             if not cache:
                 continue
             addr = cache.value_()