From: Cong Wang <xiyou.wangcong@gmail.com>
To: Borislav Petkov <bp@alien8.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-edac@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 1/2] ras: fix an off-by-one error in __find_elem()
Date: Sat, 20 Apr 2019 11:25:43 -0700 [thread overview]
Message-ID: <CAM_iQpXKWDr4AbROO=ZbkxwQHkj4anA9FJAaohOqg1SCq0L7eg@mail.gmail.com> (raw)
Message-ID: <20190420182543.KES2kIZr7Bv2vyGlN9kBLD62PZ0maSxbBs4YfUzisD4@z> (raw)
In-Reply-To: <20190420113444.GC29704@zn.tnic>
On Sat, Apr 20, 2019 at 4:34 AM Borislav Petkov <bp@alien8.de> wrote:
>
> On Tue, Apr 16, 2019 at 04:16:08PM -0700, Cong Wang wrote:
> > It is actually fairly easy:
> >
> > 1) Fill the whole page with PFN's:
> > for i in `seq 0 511`; do echo $i >> /sys/kernel/debug/ras/cec/pfn; done
> >
> > 2) Set thresh to 1 in order to trigger the deletion:
> > echo 1 > /sys/kernel/debug/ras/cec/count_threshold
> >
> > 3) Repeatedly add and remove the last element:
> > echo 512 >> /sys/kernel/debug/ras/cec/pfn
> > (until you get a crash.)
>
> Thanks, I was able to reproduce with that. Below is a conglomerate patch
> which converts __find_elem() to using Donald Knuth's binary search
> version. I don't know what I was thinking then and why I didn't use
> it from the get-go. The textbook even says that one can easily get it
> wrong...
If you want to go that far, you can choose to use lib/bsearch.c too in
case you want to reinvent the wheel.
What's your point here? You know my fix is targeted for -stable, I doubt
your 83-line change could fit for -stable.
Feel free to drop my patch to favor yours. I am really tired.
Good luck with that!
Thanks.
next prev parent reply other threads:[~2019-04-20 18:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 21:33 [v2,1/2] ras: fix an off-by-one error in __find_elem() Cong Wang
2019-04-16 21:33 ` [PATCH v2 1/2] " Cong Wang
2019-04-16 21:33 ` [v2,2/2] ras: close the race condition with timer Cong Wang
2019-04-16 21:33 ` [PATCH v2 2/2] " Cong Wang
2019-06-08 15:28 ` [tip:ras/urgent] RAS/CEC: Convert the timer callback to a workqueue tip-bot for Cong Wang
2019-04-16 21:46 ` [v2,1/2] ras: fix an off-by-one error in __find_elem() Borislav Petkov
2019-04-16 21:46 ` [PATCH v2 1/2] " Borislav Petkov
2019-04-16 23:16 ` [v2,1/2] " Cong Wang
2019-04-16 23:16 ` [PATCH v2 1/2] " Cong Wang
2019-04-20 11:34 ` [v2,1/2] " Borislav Petkov
2019-04-20 11:34 ` [PATCH v2 1/2] " Borislav Petkov
2019-04-20 18:25 ` Cong Wang [this message]
2019-04-20 18:25 ` Cong Wang
2019-04-20 19:04 ` [v2,1/2] " Borislav Petkov
2019-04-20 19:04 ` [PATCH v2 1/2] " Borislav Petkov
2019-04-20 19:15 ` [v2,1/2] " Cong Wang
2019-04-20 19:15 ` [PATCH v2 1/2] " Cong Wang
2019-04-21 8:27 ` [v2,1/2] " Borislav Petkov
2019-04-21 8:27 ` [PATCH v2 1/2] " Borislav Petkov
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