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Subject: Re: [PATCH v8 13/19] locking/rwsem: Make rwsem->owner an
 atomic_long_t
To:     Luis Henriques <lhenriques@suse.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>,
        Will Deacon <will.deacon@arm.com>,
        huang ying <huang.ying.caritas@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Jeff Layton <jlayton@kernel.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>
References: <20190520205918.22251-1-longman@redhat.com>
 <20190520205918.22251-14-longman@redhat.com>
 <20190719184538.GA20324@hermes.olymp>
 <2ed44afa-4528-a785-f188-2daf24343f97@redhat.com>
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From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <82c9383c-487f-1e13-2bbd-4767ac634a79@redhat.com>
Date:   Mon, 22 Jul 2019 22:57:04 -0400
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On 7/21/19 4:49 PM, Luis Henriques wrote:
> Waiman Long <longman@redhat.com> writes:
>
>> On 7/20/19 4:41 AM, Luis Henriques wrote:
>>> "Linus Torvalds" <torvalds@linux-foundation.org> writes:
>>>
>>>> On Fri, Jul 19, 2019 at 12:32 PM Waiman Long <longman@redhat.com> wrote:
>>>>> This patch shouldn't change the behavior of the rwsem code. The code
>>>>> only access data within the rw_semaphore structures. I don't know why it
>>>>> will cause a KASAN error. I will have to reproduce it and figure out
>>>>> exactly which statement is doing the invalid access.
>>>> The stack traces should show line numbers if you run them through
>>>> scripts/decode_stacktrace.sh.
>>>>
>>>> You need to have debug info enabled for that, though.
>>>>
>>>> Luis?
>>>>
>>>>              Linus
>>> Yep, sure.  And I should have done this in the initial report.  It's a
>>> different trace, I had to recompile the kernel.
>>>
>>> (I'm also adding Jeff to the CC list.)
>>>
>>> Cheers,
>> Thanks for the information. I think I know where the problem is. Would
>> you mind applying the attached patch to see if it can fix the KASAN error.
> Yep, that seems to work -- I can't reproduce the error anymore (and
> sorry for the delay).  Thanks!  And feel free to add my Tested-by.
>
> Cheers,

Thanks for the testing. I will post the official patch tomorrow.

Cheers,
Longman