Re: [PATCH v3 net-next 01/23] lib: add reference counting tracking infrastructure

On 12/15/21 11:41, Eric Dumazet wrote:

On Wed, Dec 15, 2021 at 2:38 AM Eric Dumazet [off-list ref] wrote:

quoted

On Wed, Dec 15, 2021 at 2:18 AM Jiri Slaby [off-list ref] wrote:

quoted

On 05. 12. 21, 5:21, Eric Dumazet wrote:

quoted

From: Eric Dumazet <redacted>

It can be hard to track where references are taken and released.

In networking, we have annoying issues at device or netns dismantles,
and we had various proposals to ease root causing them.

...

quoted

--- a/lib/Kconfig
+++ b/lib/Kconfig

@@ -680,6 +680,11 @@ config STACK_HASH_ORDER
       Select the hash size as a power of 2 for the stackdepot hash table.
       Choose a lower value to reduce the memory impact.

+config REF_TRACKER
+     bool
+     depends on STACKTRACE_SUPPORT
+     select STACKDEPOT

Hi,

I have to:
+       select STACKDEPOT_ALWAYS_INIT
here. Otherwise I see this during boot:

Thanks, I am adding Vlastimil Babka to the CC

This stuff has been added in
commit e88cc9f5e2e7a5d28a1adf12615840fab4cbebfd
Author: Vlastimil Babka [off-list ref]
Date:   Tue Dec 14 21:50:42 2021 +0000

    lib/stackdepot: allow optional init and stack_table allocation by kvmalloc()

(This is a problem because this patch is not yet in net-next, so I really do
not know how this issue should be handled)

Looks like multiple new users of stackdepot start appearing as soon as I
touch it :)

The way we solved this with a new DRM user was Andrew adding a fixup to my
patch referenced above, in his "after-next" section of mm tree.
Should work here as well.

----8<----
From 0fa1f25925c05f8c5c4f776913d84904fb4c03a1 Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <redacted>
Date: Wed, 15 Dec 2021 11:52:10 +0100
Subject: [PATCH] lib/stackdepot: allow optional init and stack_table
 allocation by kvmalloc() - fixup4

Due to 4e66934eaadc ("lib: add reference counting tracking infrastructure")
landing recently to net-next adding a new stack depot user in lib/ref_tracker.c
we need to add an appropriate call to stack_depot_init() there as well.

Signed-off-by: Vlastimil Babka <redacted>
---
 include/linux/ref_tracker.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index c11c9db5825c..60f3453be23e 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h

@@ -4,6 +4,7 @@
 #include <linux/refcount.h>
 #include <linux/types.h>
 #include <linux/spinlock.h>
+#include <linux/stackdepot.h>
 
 struct ref_tracker;
 

@@ -26,6 +27,7 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
 	spin_lock_init(&dir->lock);
 	dir->quarantine_avail = quarantine_count;
 	refcount_set(&dir->untracked, 1);
+	stack_depot_init();
 }
 
 void ref_tracker_dir_exit(struct ref_tracker_dir *dir);

-- 
2.34.1