From: yangerkun <yangerkun@huawei.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Jeff Layton <jlayton@kernel.org>
Cc: NeilBrown <neilb@suse.de>,
kernel test robot <rong.a.chen@intel.com>,
LKML <linux-kernel@vger.kernel.org>, <lkp@lists.01.org>,
Bruce Fields <bfields@fieldses.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [locks] 6d390e4b5d: will-it-scale.per_process_ops -96.6% regression
Date: Tue, 17 Mar 2020 09:41:27 +0800 [thread overview]
Message-ID: <7c8d3752-6573-ab83-d0af-f3dd4fc373f5@huawei.com> (raw)
In-Reply-To: <CAHk-=whnqDS0NJtAaArVeYQz3hcU=4Ja3auB1Jvs42eADfUgMQ@mail.gmail.com>
On 2020/3/17 1:26, Linus Torvalds wrote:
> On Mon, Mar 16, 2020 at 4:07 AM Jeff Layton <jlayton@kernel.org> wrote:
>>
>>
>> + /*
>> + * If fl_blocker is NULL, it won't be set again as this thread "owns"
>> + * the lock and is the only one that might try to claim the lock.
>> + * Because fl_blocker is explicitly set last during a delete, it's
>> + * safe to locklessly test to see if it's NULL. If it is, then we know
>> + * that no new locks can be inserted into its fl_blocked_requests list,
>> + * and we can therefore avoid doing anything further as long as that
>> + * list is empty.
>> + */
>> + if (!smp_load_acquire(&waiter->fl_blocker) &&
>> + list_empty(&waiter->fl_blocked_requests))
>> + return status;
>
> Ack. This looks sane to me now.
>
> yangerkun - how did you find the original problem?\
While try to fix CVE-2019-19769, add some log in __locks_wake_up_blocks
help me to rebuild the problem soon. This help me to discern the problem
soon.
>
> Would you mind using whatever stress test that caused commit
> 6d390e4b5d48 ("locks: fix a potential use-after-free problem when
> wakeup a waiter") with this patch? And if you did it analytically,
> you're a champ and should look at this patch too!
I will try to understand this patch, and if it's looks good to me, will
do the performance test!
Thanks
next prev parent reply other threads:[~2020-03-17 1:41 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-08 14:03 [locks] 6d390e4b5d: will-it-scale.per_process_ops -96.6% regression kernel test robot
2020-03-09 14:36 ` Jeff Layton
2020-03-09 15:52 ` Linus Torvalds
2020-03-09 17:22 ` Jeff Layton
2020-03-09 19:09 ` Jeff Layton
2020-03-09 19:53 ` Jeff Layton
2020-03-09 21:42 ` NeilBrown
2020-03-09 21:58 ` Jeff Layton
2020-03-10 7:52 ` kernel test robot
2020-03-09 22:11 ` Jeff Layton
2020-03-10 3:24 ` yangerkun
2020-03-10 7:54 ` kernel test robot
2020-03-10 12:52 ` Jeff Layton
2020-03-10 14:18 ` yangerkun
2020-03-10 15:06 ` Jeff Layton
2020-03-10 17:27 ` Jeff Layton
2020-03-10 21:01 ` NeilBrown
2020-03-10 21:14 ` Jeff Layton
2020-03-10 21:21 ` NeilBrown
2020-03-10 21:47 ` Linus Torvalds
2020-03-10 22:07 ` Jeff Layton
2020-03-10 22:31 ` Linus Torvalds
2020-03-11 22:22 ` NeilBrown
2020-03-12 0:38 ` Linus Torvalds
2020-03-12 4:42 ` NeilBrown
2020-03-12 12:31 ` Jeff Layton
2020-03-12 22:19 ` NeilBrown
2020-03-14 1:11 ` Jeff Layton
2020-03-12 16:07 ` Linus Torvalds
2020-03-14 1:31 ` Jeff Layton
2020-03-14 2:31 ` NeilBrown
2020-03-14 15:58 ` Linus Torvalds
2020-03-15 13:54 ` Jeff Layton
2020-03-16 5:06 ` NeilBrown
2020-03-16 11:07 ` Jeff Layton
2020-03-16 17:26 ` Linus Torvalds
2020-03-17 1:41 ` yangerkun [this message]
2020-03-17 14:05 ` yangerkun
2020-03-17 16:07 ` Jeff Layton
2020-03-18 1:09 ` yangerkun
2020-03-19 17:51 ` Jeff Layton
2020-03-19 19:23 ` Linus Torvalds
2020-03-19 19:24 ` Jeff Layton
2020-03-19 19:35 ` Linus Torvalds
2020-03-19 20:10 ` Jeff Layton
2020-03-16 22:45 ` NeilBrown
2020-03-17 15:59 ` Jeff Layton
2020-03-17 21:27 ` NeilBrown
2020-03-18 5:12 ` kernel test robot
2020-03-16 4:26 ` NeilBrown
2020-03-11 1:57 ` yangerkun
2020-03-11 12:52 ` Jeff Layton
2020-03-11 13:26 ` yangerkun
2020-03-11 22:15 ` NeilBrown
2020-03-10 7:50 ` kernel test robot
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