From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
stable@vger.kernel.org, Petr Mladek <pmladek@suse.com>
Subject: Re: printk: queue wake_up_klogd irq_work only if per-CPU areas are ready
Date: Tue, 14 Apr 2020 22:13:09 +0900 [thread overview]
Message-ID: <20200414131309.GE12779@google.com> (raw)
In-Reply-To: <20200414121412.GA605766@kroah.com>
On (20/04/14 14:14), Greg KH wrote:
> On Tue, Apr 14, 2020 at 09:06:13PM +0900, Sergey Senozhatsky wrote:
> > Hello,
> >
> > Commit ab6f762f0f53162d41 Linus' HEAD.
> >
> > printk_deferred() does not make sure that it's safe to write to
> > per-CPU data, which causes problems when printk_deferred() is
> > invoked "too early", before per-CPU areas are initialized. There
> > are multiple bug reports, e.g.
> > https://bugzilla.kernel.org/show_bug.cgi?id=206847
> >
> > -ss
>
> So where do you want this commit backported to?
Well, printk() is affected in all the kernels where
printk_deferred() relies on per-CPU data. Which may
translate to "pretty much all current stable kernels?"
This patch, however, uses printk_safe() bits, so it
won't apply on pre-printk_safe() kernels (not sure if
we have such -stable kernels though).
-ss
next prev parent reply other threads:[~2020-04-14 13:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 12:06 printk: queue wake_up_klogd irq_work only if per-CPU areas are ready Sergey Senozhatsky
2020-04-14 12:14 ` Greg KH
2020-04-14 13:13 ` Sergey Senozhatsky [this message]
2020-07-20 12:50 ` Greg KH
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