From: Mike Rapoport <rppt@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Denis V. Lunev" <den@virtuozzo.com>,
"Denis V. Lunev" <den@openvz.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, Juergen Gross <jgross@suse.com>,
Kiryl Shutsemau <kas@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/mm/pat: take cpa_lock around large-page collapse
Date: Sat, 11 Jul 2026 11:47:11 +0300 [thread overview]
Message-ID: <alIDD0_ggoIovmTX@kernel.org> (raw)
In-Reply-To: <a33dce28-596f-4a4b-bd39-f3b2ad9f0d73@intel.com>
On Fri, Jul 10, 2026 at 10:15:54AM -0700, Dave Hansen wrote:
> cpa_collapse_large_pages() seems to be a never ending source of bugs.
Yeah, this one, the race with ptdump and a year old issue on Xen PV.
There might be more of course but I wouldn't call it endless.
> I'm tempted to say we should just axe it, call it a failed experiment,
> and move on with life.
>
> Is it worth keeping?
This what lets keeping executable mappings in 2M granularity. Modules,
ftrace and kprobes are already using it and BPF is on the way:
https://lore.kernel.org/bpf/20260626-execmem-x86-rox-bpf-v0-v1-0-45a0b0ed4fe9@kernel.org/
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2026-07-11 8:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-26 16:32 [PATCH] x86/mm/pat: take cpa_lock around large-page collapse Denis V. Lunev
2026-07-02 17:47 ` Denis V. Lunev
2026-07-03 13:01 ` Kiryl Shutsemau
2026-07-10 16:15 ` Denis V. Lunev
2026-07-10 17:15 ` Dave Hansen
2026-07-11 8:47 ` Mike Rapoport [this message]
2026-07-10 17:13 ` Dave Hansen
2026-07-11 8:56 ` Mike Rapoport
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