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Groups > linux.kernel > #1530329
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function |
| Date | 2016-11-25 16:20 +0100 |
| Message-ID | <sHqsa-2er-19@gated-at.bofh.it> (permalink) |
| References | <swVfX-3Pm-11@gated-at.bofh.it> <swVfY-3Pm-23@gated-at.bofh.it> <sHqsa-2er-21@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Nov 25, 2016 at 04:01:13PM +0100, Petr Mladek wrote:
> On Fri 2016-10-28 00:49:33, Sergey Senozhatsky wrote:
> > 2) Since commit cf9b1106c81c ("printk/nmi: flush NMI messages on the
> > system panic") panic attempts to zap the `logbuf_lock' spin_lock to
> > successfully flush nmi messages to `logbuf'.
>
> Note that the same code is newly used to flush also the printk_safe
> per-CPU buffers. It means that logbuf_lock is zapped also when
> flushing these new buffers.
>
Note that (raw_)spin_lock_init() as done here and in
printk_nmi_flush_on_panic() can wreck the lock state and doesn't ensure
a subsequent spin_lock() of said lock will actually work.
The very best solution is to simply ignore the lock in panic situations
rather than trying to wreck it.
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Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Petr Mladek <pmladek@suse.com> - 2016-11-25 16:20 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Peter Zijlstra <peterz@infradead.org> - 2016-11-25 16:20 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-12-01 03:40 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Peter Zijlstra <peterz@infradead.org> - 2016-12-01 06:50 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Petr Mladek <pmladek@suse.com> - 2016-12-01 14:40 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-12-02 02:20 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-12-01 03:20 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-12-01 14:00 +0100
Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function Petr Mladek <pmladek@suse.com> - 2016-12-01 14:20 +0100
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