From: Byungchul Park <max.byungchul.park@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>,
Ingo Molnar <mingo@kernel.org>,
tglx@linutronix.de, Michel Lespinasse <walken@google.com>,
boqun.feng@gmail.com, kirill@shutemov.name,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, akpm@linux-foundation.org,
willy@infradead.org, npiggin@gmail.com, kernel-team@lge.com
Subject: Re: [PATCH v7 06/16] lockdep: Detect and handle hist_lock ring buffer overwrite
Date: Thu, 13 Jul 2017 20:19:14 +0900 [thread overview]
Message-ID: <CANrsvRNAeL=Xdrbg5k56o5pC_p05LN7=rSrXLTHBJiXXFXk5Mw@mail.gmail.com> (raw)
In-Reply-To: <20170713102905.ysrvn7td6ryt4jaj@hirez.programming.kicks-ass.net>
On Thu, Jul 13, 2017 at 7:29 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Jul 13, 2017 at 07:09:53PM +0900, Byungchul Park wrote:
>> On Thu, Jul 13, 2017 at 11:50:52AM +0200, Peter Zijlstra wrote:
>> > wait_for_completion(&C);
>> > atomic_inc_return();
>> >
>> > mutex_lock(A1);
>> > mutex_unlock(A1);
>> >
>> >
>> > <IRQ>
>> > spin_lock(B1);
>> > spin_unlock(B1);
>> >
>> > ...
>> >
>> > spin_lock(B64);
>> > spin_unlock(B64);
>> > </IRQ>
>> >
>> >
>> > mutex_lock(A2);
>> > mutex_unlock(A2);
>> >
>> > complete(&C);
>> >
>> >
>> > That gives:
>> >
>> > xhist[ 0] = A1
>>
>> We have to rollback here later on irq_exit.
>>
>> The followings are ones for irq context.
>>
>> > xhist[ 1] = B1
>> > ...
>> > xhist[63] = B63
>> >
>> > then we wrap and have:
>> >
>> > xhist[0] = B64
>> >
>> > then we rewind to 1 and invalidate to arrive at:
>> >
>>
>> Now, whether xhist[0] has been overwritten or not is important. If yes,
>> xhist[0] should be NULL, _not_ xhist[1], which is one for irq context so
>> not interest at all.
>>
>> > xhist[ 0] = B64
>> > xhist[ 1] = NULL <-- idx
>>
>> Therefore, it should be,
>>
>> xhist[ 0] = NULL <- invalidate, cannot use it any more
>> --- <- on returning back from irq context, start from here
>> xhist[ 1] = B1 <-- obsolete history of irq
>
> Ah, so you rely on the same_context_xhlock() ? That doesn't work for
> hist (formerly work).
As I mentioned in cover-letter, I applied the rollback mechanism into work
(of workqueue) as well. So it works even for hist.
--
Thanks,
Byungchul
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next prev parent reply other threads:[~2017-07-13 11:19 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 8:59 [PATCH v7 00/16] lockdep: Implement crossrelease feature Byungchul Park
2017-05-24 8:59 ` [PATCH v7 01/16] lockdep: Refactor lookup_chain_cache() Byungchul Park
2017-05-24 8:59 ` [PATCH v7 02/16] lockdep: Add a function building a chain between two classes Byungchul Park
2017-05-24 8:59 ` [PATCH v7 03/16] lockdep: Change the meaning of check_prev_add()'s return value Byungchul Park
2017-05-24 8:59 ` [PATCH v7 04/16] lockdep: Make check_prev_add() able to handle external stack_trace Byungchul Park
2017-05-24 8:59 ` [PATCH v7 05/16] lockdep: Implement crossrelease feature Byungchul Park
2017-06-13 0:33 ` Byungchul Park
2017-06-22 23:27 ` Byungchul Park
2017-07-11 16:04 ` Peter Zijlstra
2017-07-12 2:24 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 06/16] lockdep: Detect and handle hist_lock ring buffer overwrite Byungchul Park
2017-07-11 16:12 ` Peter Zijlstra
2017-07-12 2:00 ` Byungchul Park
2017-07-12 7:56 ` Peter Zijlstra
2017-07-13 2:07 ` Byungchul Park
2017-07-13 8:14 ` Peter Zijlstra
2017-07-13 8:57 ` Byungchul Park
2017-07-13 9:50 ` Peter Zijlstra
2017-07-13 10:09 ` Byungchul Park
2017-07-13 10:29 ` Peter Zijlstra
2017-07-13 11:12 ` Peter Zijlstra
2017-07-13 11:23 ` Byungchul Park
2017-07-14 1:41 ` Byungchul Park
2017-07-14 6:42 ` Byungchul Park
2017-07-21 13:54 ` Peter Zijlstra
2017-07-25 6:29 ` Byungchul Park
2017-07-25 8:45 ` Peter Zijlstra
2017-07-13 11:19 ` Byungchul Park [this message]
2017-07-18 1:25 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 07/16] lockdep: Handle non(or multi)-acquisition of a crosslock Byungchul Park
2017-05-24 8:59 ` [PATCH v7 08/16] lockdep: Avoid adding redundant direct links of crosslocks Byungchul Park
2017-07-25 15:41 ` Peter Zijlstra
2017-07-26 7:16 ` Byungchul Park
2017-05-24 8:59 ` [PATCH v7 09/16] lockdep: Fix incorrect condition to print bug msgs for MAX_LOCKDEP_CHAIN_HLOCKS Byungchul Park
2017-05-24 8:59 ` [PATCH v7 10/16] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park
2017-05-24 8:59 ` [PATCH v7 11/16] lockdep: Apply crossrelease to completions Byungchul Park
2017-05-24 8:59 ` [PATCH v7 12/16] pagemap.h: Remove trailing white space Byungchul Park
2017-05-24 8:59 ` [PATCH v7 13/16] lockdep: Apply crossrelease to PG_locked locks Byungchul Park
2017-05-24 8:59 ` [PATCH v7 14/16] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2017-05-24 8:59 ` [PATCH v7 15/16] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2017-05-24 8:59 ` [PATCH v7 16/16] lockdep: Crossrelease feature documentation Byungchul Park
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