From: Byungchul Park <byungchul.park@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Byungchul Park <max.byungchul.park@gmail.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: Tue, 25 Jul 2017 15:29:45 +0900 [thread overview]
Message-ID: <20170725062945.GM20323@X58A-UD3R> (raw)
In-Reply-To: <20170721135420.gadjqv6hian4yzgq@hirez.programming.kicks-ass.net>
On Fri, Jul 21, 2017 at 03:54:20PM +0200, Peter Zijlstra wrote:
> On Fri, Jul 14, 2017 at 03:42:10PM +0900, Byungchul Park wrote:
> > On Thu, Jul 13, 2017 at 08:23:33PM +0900, Byungchul Park wrote:
> > > On Thu, Jul 13, 2017 at 8:12 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > > > On Thu, Jul 13, 2017 at 12:29:05PM +0200, Peter Zijlstra 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>
> > > >> > >
> > > >> > >
> > > >
> > > > Also consider the alternative:
> > > >
> > > > <IRQ>
> > > > spin_lock(D);
> > > > spin_unlock(D);
> > > >
> > > > complete(&C);
> > > > </IRQ>
> > > >
> > > > in which case the context test will also not work.
> > >
> > > Context tests are done on xhlock with the release context, _not_
> > > acquisition context. For example, spin_lock(D) and complete(&C) are
> > > in the same context, so the test would pass in this example.
>
> The point was, this example will also link C to B*.
_No_, as I already said.
> (/me copy paste from older email)
>
> That gives:
>
> xhist[ 0] = A1
> xhist[ 1] = B1
> ...
> xhist[63] = B63
>
> then we wrap and have:
>
> xhist[0] = B64
>
> then we rewind to 1 and invalidate to arrive at:
We invalidate xhist[_0_], as I already said.
> xhist[ 0] = B64
> xhist[ 1] = NULL <-- idx
> xhist[ 2] = B2
> ...
> xhist[63] = B63
>
>
> Then we do D and get
>
> xhist[ 0] = B64
> xhist[ 1] = D <-- idx
> xhist[ 2] = B2
> ...
> xhist[63] = B63
We should get
xhist[ 0] = NULL
xhist[ 1] = D <-- idx
xhist[ 2] = B2
...
xhist[63] = B63
By the way, did not you get my reply? I did exactly same answer.
Perhaps You have not received or read my replies.
> And now there is nothing that will invalidate B*, after all, the
> gen_id's are all after C's stamp, and the same_context_xhlock() test
> will also pass because they're all from IRQ context (albeit not the
> same, but it cannot tell).
It will stop at xhist[0] because it has been invalidated.
> Does this explain? Or am I still missing something?
Could you read the following reply? Not enough?
https://lkml.org/lkml/2017/7/13/214
I am sorry if my english makes you hard to understand. But I already
answered all you asked.
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next prev parent reply other threads:[~2017-07-25 6:30 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 [this message]
2017-07-25 8:45 ` Peter Zijlstra
2017-07-13 11:19 ` Byungchul Park
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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