mm/slub: use stackdepot to save stack trace in objects

Many stack traces are similar so there are many similar arrays.
Stackdepot saves each unique stack only once.

Replace field addrs in struct track with depot_stack_handle_t handle.  Use
stackdepot to save stack trace.

The benefits are smaller memory overhead and possibility to aggregate
per-cache statistics in the following patch using the stackdepot handle
instead of matching stacks manually.

[ vbabka@suse.cz: rebase to 5.17-rc1 and adjust accordingly ]

This was initially merged as commit 788691464c29 and reverted by commit
ae14c63a9f20 due to several issues, that should now be fixed.
The problem of unconditional memory overhead by stackdepot has been
addressed by commit 2dba5eb1c73b ("lib/stackdepot: allow optional init
and stack_table allocation by kvmalloc()"), so the dependency on
stackdepot will result in extra memory usage only when a slab cache
tracking is actually enabled, and not for all CONFIG_SLUB_DEBUG builds.
The build failures on some architectures were also addressed, and the
reported issue with xfs/433 test did not reproduce on 5.17-rc1 with this
patch.

Signed-off-by: Oliver Glitta <glittao@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 6ee64d6208b3..73943479a2b7 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -24,6 +24,7 @@
 #include <asm/tlbflush.h>
 #include <asm/page.h>
 #include <linux/memcontrol.h>
+#include <linux/stackdepot.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kmem.h>
@@ -314,9 +315,13 @@ kmem_cache_create_usercopy(const char *name,
 	 * If no slub_debug was enabled globally, the static key is not yet
 	 * enabled by setup_slub_debug(). Enable it if the cache is being
 	 * created with any of the debugging flags passed explicitly.
+	 * It's also possible that this is the first cache created with
+	 * SLAB_STORE_USER and we should init stack_depot for it.
 	 */
 	if (flags & SLAB_DEBUG_FLAGS)
 		static_branch_enable(&slub_debug_enabled);
+	if (flags & SLAB_STORE_USER)
+		stack_depot_init();
 #endif
 
 	mutex_lock(&slab_mutex);