linux-kernel - Re: [PATCH v8 13/19] locking/rwsem: Make rwsem->owner an atomic_long

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Message-ID: <81e82d5b-5074-77e8-7204-28479bbe0df0@redhat.com>
Date:   Sat, 20 Jul 2019 11:04:10 -0400
From:   Waiman Long <longman@...hat.com>
To:     Luis Henriques <lhenriques@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Borislav Petkov <bp@...en8.de>, Will Deacon <will.deacon@....com>,
        huang ying <huang.ying.caritas@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Jeff Layton <jlayton@...nel.org>
Subject: Re: [PATCH v8 13/19] locking/rwsem: Make rwsem->owner an
 atomic_long_t

On 7/20/19 4:41 AM, Luis Henriques wrote:
> "Linus Torvalds" <torvalds@...ux-foundation.org> writes:
>
>> On Fri, Jul 19, 2019 at 12:32 PM Waiman Long <longman@...hat.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.

Thanks,
Longman



View attachment "0001-locking-rwsem-Don-t-call-owner_on_cpu-on-read-owner.patch" of type "text/x-patch" (1808 bytes)