From: Vlastimil Babka <vbabka@suse.cz>
To: Marco Elver <elver@google.com>, Daniel Latypov <dlatypov@google.com>
Cc: glittao@gmail.com, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
KUnit Development <kunit-dev@googlegroups.com>,
Brendan Higgins <brendanhiggins@google.com>
Subject: Re: [PATCH v3 1/2] kunit: add a KUnit test for SLUB debugging functionality
Date: Tue, 6 Apr 2021 12:57:54 +0200 [thread overview]
Message-ID: <11886d4f-8826-0cd6-b5fd-defc65470ed5@suse.cz> (raw)
In-Reply-To: <CANpmjNPhWUsQrG62Z2jchdqzgSOfVYOsD1QDJpRghJwzwRZcQA@mail.gmail.com>
On 4/1/21 11:24 PM, Marco Elver wrote:
> On Thu, 1 Apr 2021 at 21:04, Daniel Latypov <dlatypov@google.com> wrote:
>> > }
>> > #else
>> > static inline bool slab_add_kunit_errors(void) { return false; }
>> > #endif
>> >
>> > And anywhere you want to increase the error count, you'd call
>> > slab_add_kunit_errors().
>> >
>> > Another benefit of this approach is that if KUnit is disabled, there is
>> > zero overhead and no additional code generated (vs. the current
>> > approach).
>>
>> The resource approach looks really good, but...
>> You'd be picking up a dependency on
>> https://lore.kernel.org/linux-kselftest/20210311152314.3814916-2-dlatypov@google.com/
>> current->kunit_test will always be NULL unless CONFIG_KASAN=y &&
>> CONFIG_KUNIT=y at the moment.
>> My patch drops the CONFIG_KASAN requirement and opens it up to all tests.
>
> Oh, that's a shame, but hopefully it'll be in -next soon.
>
>> At the moment, it's just waiting another look over from Brendan or David.
>> Any ETA on that, folks? :)
>>
>> So if you don't want to get blocked on that for now, I think it's fine to add:
>> #ifdef CONFIG_SLUB_KUNIT_TEST
>> int errors;
>> #endif
>
> Until kunit fixes setting current->kunit_test, a cleaner workaround
> that would allow to do the patch with kunit_resource, is to just have
> an .init/.exit function that sets it ("current->kunit_test = test;").
> And then perhaps add a note ("FIXME: ...") to remove it once the above
> patch has landed.
>
> At least that way we get the least intrusive change for mm/slub.c, and
> the test is the only thing that needs a 2-line patch to clean up
> later.
So when testing internally Oliver's new version with your suggestions (thanks
again for those), I got lockdep splats because slab_add_kunit_errors is called
also from irq disabled contexts, and kunit_find_named_resource will call
spin_lock(&test->lock) that's not irq safe. Can we make the lock irq safe? I
tried the change below and it makde the problem go away. If you agree, the
question is how to proceed - make it part of Oliver's patch series and let
Andrew pick it all with eventually kunit team's acks on this patch, or whatnot.
----8<----
commit ab28505477892e9824c57ac338c88aec2ec0abce
Author: Vlastimil Babka <vbabka@suse.cz>
Date: Tue Apr 6 12:28:07 2021 +0200
kunit: make test->lock irq safe
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 49601c4b98b8..524d4789af22 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -515,8 +515,9 @@ kunit_find_resource(struct kunit *test,
void *match_data)
{
struct kunit_resource *res, *found = NULL;
+ unsigned long flags;
- spin_lock(&test->lock);
+ spin_lock_irqsave(&test->lock, flags);
list_for_each_entry_reverse(res, &test->resources, node) {
if (match(test, res, (void *)match_data)) {
@@ -526,7 +527,7 @@ kunit_find_resource(struct kunit *test,
}
}
- spin_unlock(&test->lock);
+ spin_unlock_irqrestore(&test->lock, flags);
return found;
}
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index ec9494e914ef..2c62eeb45b82 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -442,6 +442,7 @@ int kunit_add_resource(struct kunit *test,
void *data)
{
int ret = 0;
+ unsigned long flags;
res->free = free;
kref_init(&res->refcount);
@@ -454,10 +455,10 @@ int kunit_add_resource(struct kunit *test,
res->data = data;
}
- spin_lock(&test->lock);
+ spin_lock_irqsave(&test->lock, flags);
list_add_tail(&res->node, &test->resources);
/* refcount for list is established by kref_init() */
- spin_unlock(&test->lock);
+ spin_unlock_irqrestore(&test->lock, flags);
return ret;
}
@@ -515,9 +516,11 @@ EXPORT_SYMBOL_GPL(kunit_alloc_and_get_resource);
void kunit_remove_resource(struct kunit *test, struct kunit_resource *res)
{
- spin_lock(&test->lock);
+ unsigned long flags;
+
+ spin_lock_irqsave(&test->lock, flags);
list_del(&res->node);
- spin_unlock(&test->lock);
+ spin_unlock_irqrestore(&test->lock, flags);
kunit_put_resource(res);
}
EXPORT_SYMBOL_GPL(kunit_remove_resource);
@@ -597,6 +600,7 @@ EXPORT_SYMBOL_GPL(kunit_kfree);
void kunit_cleanup(struct kunit *test)
{
struct kunit_resource *res;
+ unsigned long flags;
/*
* test->resources is a stack - each allocation must be freed in the
@@ -608,9 +612,9 @@ void kunit_cleanup(struct kunit *test)
* protect against the current node being deleted, not the next.
*/
while (true) {
- spin_lock(&test->lock);
+ spin_lock_irqsave(&test->lock, flags);
if (list_empty(&test->resources)) {
- spin_unlock(&test->lock);
+ spin_unlock_irqrestore(&test->lock, flags);
break;
}
res = list_last_entry(&test->resources,
@@ -621,7 +625,7 @@ void kunit_cleanup(struct kunit *test)
* resource, and this can't happen if the test->lock
* is held.
*/
- spin_unlock(&test->lock);
+ spin_unlock_irqrestore(&test->lock, flags);
kunit_remove_resource(test, res);
}
#if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
next prev parent reply other threads:[~2021-04-06 10:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-31 8:51 [PATCH v3 1/2] kunit: add a KUnit test for SLUB debugging functionality glittao
2021-03-31 8:51 ` [PATCH v3 2/2] slub: remove resiliency_test() function glittao
2021-04-01 7:41 ` [PATCH v3 1/2] kunit: add a KUnit test for SLUB debugging functionality Vlastimil Babka
2021-04-01 9:16 ` Marco Elver
2021-04-01 19:04 ` Daniel Latypov
2021-04-01 21:24 ` Marco Elver
2021-04-06 10:57 ` Vlastimil Babka [this message]
2021-04-08 10:29 ` Marco Elver
2021-04-08 17:19 ` Daniel Latypov
2021-04-09 7:54 ` Brendan Higgins
2021-04-02 9:38 ` Brendan Higgins
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=11886d4f-8826-0cd6-b5fd-defc65470ed5@suse.cz \
--to=vbabka@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=brendanhiggins@google.com \
--cc=cl@linux.com \
--cc=dlatypov@google.com \
--cc=elver@google.com \
--cc=glittao@gmail.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=kunit-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).