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Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the debug code

From Byungchul Park <byungchul.park@lge.com>
Newsgroups linux.kernel
Subject Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the debug code
Date 2016-01-29 08:00 +0100
Message-ID <qWbce-7k1-5@gated-at.bofh.it> (permalink)
References (5 earlier) <qVSjg-28z-25@gated-at.bofh.it> <qVSsW-2cx-19@gated-at.bofh.it> <qVWZA-5wF-17@gated-at.bofh.it> <qW3Ro-28Y-31@gated-at.bofh.it> <qW56P-2Vm-3@gated-at.bofh.it>
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On Fri, Jan 29, 2016 at 09:27:03AM +0900, Sergey Senozhatsky wrote:
> 
> well, the stack is surely limited, but on every
> spin_dump()->spin_lock() recursive call it does another
> round of
> 
> 	u64 loops = loops_per_jiffy * HZ;
> 
> 	for (i = 0; i < loops; i++) {
> 		if (arch_spin_trylock(&lock->raw_lock))
> 			return;
> 		__delay(1);
> 	}
> 
> so if you have 1000 spin_dump()->spin_lock() then, well,
> something has been holding the lock for '1000 * loops_per_jiffy * HZ'.

Or the printk() is heavily called and the lock is congested.

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Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-28 03:00 +0100
  Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-28 03:40 +0100
    RE: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the debug code "byungchul.park" <byungchul.park@lge.com> - 2016-01-28 06:00 +0100
      Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-28 07:10 +0100
        Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-28 09:30 +0100
          Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-28 11:50 +0100
            Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-28 12:00 +0100
              Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-01-28 16:50 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the  debug code Peter Hurley <peter@hurleysoftware.com> - 2016-01-29 00:10 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-29 01:00 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 02:00 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-29 04:10 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 05:10 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-29 13:20 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 01:30 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the  debug code Peter Hurley <peter@hurleysoftware.com> - 2016-01-29 05:40 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 06:30 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the  debug code Peter Hurley <peter@hurleysoftware.com> - 2016-01-29 06:50 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 07:20 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 07:40 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-31 13:30 +0100
                [PATCH 2/3] printk: introduce reset_console_drivers() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-31 13:40 +0100
                Re: [PATCH 2/3] printk: introduce reset_console_drivers() kbuild test robot <lkp@intel.com> - 2016-01-31 13:50 +0100
                [PATCH 1/3] printk: introduce console_reset_on_panic() function Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-31 13:40 +0100
                [PATCH 3/3] spinlock_debug: panic on recursive lock spin_dump() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-31 13:40 +0100
                Re: [PATCH 3/3] spinlock_debug: panic on recursive lock spin_dump() Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-02-01 17:20 +0100
                Re: [PATCH 3/3] spinlock_debug: panic on recursive lock spin_dump() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-02 09:00 +0100
                Re: [PATCH 1/3] printk: introduce console_reset_on_panic() function kbuild test robot <lkp@intel.com> - 2016-01-31 13:50 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-29 08:00 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-29 08:20 +0100
                Re: [PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in  the debug code Byungchul Park <byungchul.park@lge.com> - 2016-01-29 09:20 +0100

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