linux-kernel - Re: [PATCH 2.6.32 18/62] s390/hibernate: fix save and restore of kernel text section

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Message-ID: <20150915060927.GA4051@osiris>
Date:	Tue, 15 Sep 2015 08:09:27 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	Willy Tarreau <w@....eu>, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org, Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [PATCH 2.6.32 18/62] s390/hibernate: fix save and restore of
 kernel text section

On Tue, Sep 15, 2015 at 03:10:45AM +0100, Ben Hutchings wrote:
> On Sun, 2015-09-13 at 00:56 +0200, Willy Tarreau wrote:
> > 2.6.32-longterm review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Heiko Carstens <heiko.carstens@...ibm.com>
> > 
> > commit d74419495633493c9cd3f2bbeb7f3529d0edded6 upstream.
> > 
> > Sebastian reported a crash caused by a jump label mismatch after resume.
> > This happens because we do not save the kernel text section during suspend
> > and therefore also do not restore it during resume, but use the kernel image
> > that restores the old system.
> [...]
> 
> I don't think this is needed because jump labels aren't implemented in
> 2.6.32.  But maybe there was some other mechanism that changes the
> kernel text on s390?

Broken jump labels were the symptons when the problem was reported. However
we lose everything that modifies kernel text without this patch.
If it's not jump labels then there is still kprobes around where we have
the same problem.
Probably the patch description should have been better.

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