linux-kernel - Re: [PATCH 0/1] alpha: fix user-space corruption during memory compaction

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Message-ID: <aW8yQMNTNEfxu6Fn@creeky>
Date: Tue, 20 Jan 2026 20:44:00 +1300
From: Michael Cree <mcree@...on.net.nz>
To: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Cc: Magnus Lindholm <linmag7@...il.com>, linux-kernel@...r.kernel.org,
	linux-alpha@...r.kernel.org, hch@...radead.org, macro@...am.me.uk,
	mattst88@...il.com, richard.henderson@...aro.org, ink@...een.parts
Subject: Re: [PATCH 0/1] alpha: fix user-space corruption during memory
 compaction

On Fri, Jan 02, 2026 at 06:57:28PM +0100, John Paul Adrian Glaubitz wrote:
> Hi Magnus,
> 
> On Fri, 2026-01-02 at 18:30 +0100, Magnus Lindholm wrote:
> > This patch fixes long-standing user-space crashes on Alpha systems
> > when memory compaction is enabled.
> > 
> > Observed symptoms include:
> >   - sporadic SIGSEGV in unrelated user programs
> >   - glibc allocator failures (e.g. "unaligned tcache chunk detected")
> >   - gcc "internal compiler error"
> >   - heap corruption detected by malloc consistency checks
> > 
> > The failures occur only when page migration / compaction is active
> > and disappear when compaction is disabled. They affect both UP and
> > SMP kernels and are not specific to a particular Alpha CPU model.
> 
> Wow, thanks for fixing this! This has been indeed a longstanding issue and
> seeing it fixed would be great.
> 
> I'm CC'ing Michael Cree who has been observing the issue as well and could
> help testing your series.

I've successfully run a 6.18.3 kernel with this patch and
CONFIG_COMPACTION on for almost four days on an XP1000 without
any problem. I would normally see one of the observed problems
described above within a day, and certainly within two days, when
running with a bad kernel, so this is looking good.

Feel free to add:

Tested-by: Michael Cree <mcree@...on.net.nz>

Cheers,
Michael.