Extend the slub_debug syntax to "slub_debug=<flags>[,<slub>]*", where <slub>
may contain an asterisk at the end. For example, the following would poison
all kmalloc slabs:
slub_debug=P,kmalloc*
and the following would apply the default flags to all kmalloc and all block IO
slabs:
slub_debug=,bio*,kmalloc*
Please note that a similar patch was posted by Iliyan Malchev some time ago but
was never merged:
https://marc.info/?l=linux-mm&m=131283905330474&w=2
Signed-off-by: Aaron Tomlin <atom...@redhat.com>
---
Changes from v2 [2]:
- Add a function and kernel-doc comment
- Refactor code
- Use the appropriate helper function max_t()
Changes from v1 [1]:
- Add appropriate cast to address compiler warning
[1]: https://marc.info/?l=linux-kernel&m=153657804506284&w=2
[2]: https://marc.info/?l=linux-kernel&m=153747362316965&w=2
---
Documentation/vm/slub.rst | 12 +++++++++---
mm/slub.c | 50 +++++++++++++++++++++++++++++++++++++++++------
2 files changed, 53 insertions(+), 9 deletions(-)
diff --git a/Documentation/vm/slub.rst b/Documentation/vm/slub.rst
index 3a775fd64e2d..195928808bac 100644
--- a/Documentation/vm/slub.rst
+++ b/Documentation/vm/slub.rst
@@ -36,9 +36,10 @@ debugging is enabled. Format:
slub_debug=<Debug-Options>
Enable options for all slabs
-slub_debug=<Debug-Options>,<slab name>
- Enable options only for select slabs
+slub_debug=<Debug-Options>,<slab name1>,<slab name2>,...
+ Enable options only for select slabs (no spaces
+ after a comma)
Possible debug options are::
@@ -62,7 +63,12 @@ Trying to find an issue in the dentry cache? Try::
slub_debug=,dentry
-to only enable debugging on the dentry cache.
+to only enable debugging on the dentry cache. You may use an asterisk at the
+end of the slab name, in order to cover all slabs with the same prefix. For
+example, here's how you can poison the dentry cache as well as all kmalloc
+slabs:
+
+ slub_debug=P,kmalloc-*,dentry
Red zoning and tracking may realign the slab. We can just apply sanity checks
to the dentry cache with::
diff --git a/mm/slub.c b/mm/slub.c
index 8da34a8af53d..7927f971df0d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1276,16 +1276,54 @@ static int __init setup_slub_debug(char *str)
__setup("slub_debug", setup_slub_debug);
+/*
+ * kmem_cache_flags - apply debugging options to the cache
+ * @object_size: the size of an object without meta data
+ * @flags: flags to set
+ * @name: name of the cache
+ * @ctor: constructor function
+ *
+ * Debug option(s) are applied to @flags. In addition to the debug
+ * option(s), if a slab name (or multiple) is specified i.e.
+ * slub_debug=<Debug-Options>,<slab name1>,<slab name2> ...
+ * then only the select slabs will receive the debug option(s).
+ */
slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name,
void (*ctor)(void *))
{
- /*
- * Enable debugging if selected on the kernel commandline.
- */
- if (slub_debug && (!slub_debug_slabs || (name &&
- !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))))
- flags |= slub_debug;
+ char *iter;
+ size_t len;
+
+ /* If slub_debug = 0, it folds into the if conditional. */
+ if (!slub_debug_slabs)
+ return flags | slub_debug;
+
+ len = strlen(name);
+ iter = slub_debug_slabs;
+ while (*iter) {
+ char *end, *glob;
+ size_t cmplen;
+
+ end = strchr(iter, ',');
+ if (!end)
+ end = iter + strlen(iter);
+
+ glob = strnchr(iter, end - iter, '*');
+ if (glob)
+ cmplen = glob - iter;
+ else
+ cmplen = max_t(size_t, len, (end - iter));
+
+ if (!strncmp(name, iter, cmplen)) {
+ flags |= slub_debug;
+ break;
+ }
+
+ if (!*end)
+ break;
+ iter = end + 1;
+ }
return flags;
}
--
2.14.4
