linux-kernel - Re: [PATCH] resource,kexec: walk_system_ram_res

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Message-ID: <ZxJoLxyfAHxd18UM@MiWiFi-R3L-srv>
Date: Fri, 18 Oct 2024 21:52:47 +0800
From: Baoquan He <bhe@...hat.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Gregory Price <gourry@...rry.net>, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	bhelgaas@...gle.com, ilpo.jarvinen@...ux.intel.com,
	mika.westerberg@...ux.intel.com, ying.huang@...el.com,
	tglx@...utronix.de, takahiro.akashi@...aro.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] resource,kexec: walk_system_ram_res_rev must retain
 resource flags

On 10/18/24 at 03:22pm, Andy Shevchenko wrote:
> On Fri, Oct 18, 2024 at 10:18:42AM +0800, Baoquan He wrote:
> > HI Gregory,
> > 
> > On 10/17/24 at 03:03pm, Gregory Price wrote:
> > > walk_system_ram_res_rev() erroneously discards resource flags when
> > > passing the information to the callback.
> > > 
> > > This causes systems with IORESOURCE_SYSRAM_DRIVER_MANAGED memory to
> > > have these resources selected during kexec to store kexec buffers
> > > if that memory happens to be at placed above normal system ram.
> > 
> > Sorry about that. I haven't checked IORESOURCE_SYSRAM_DRIVER_MANAGED
> > memory carefully, wondering if res could be set as
> > 'IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY' plus
> > IORESOURCE_SYSRAM_DRIVER_MANAGED in iomem_resource tree.
> > 
> > Anyway, the change in this patch is certainly better. Thanks.
> 
> Can we get more test cases in the respective module, please?

Do you mean testing CXL memory in kexec/kdump? No, we can't. Kexec/kdump
test cases basically is system testing, not unit test or module test. It
needs run system and then jump to 2nd kernel, vm can be used but it
can't cover many cases existing only on baremetal. Currenly, Redhat's
CKI is heavily relied on to test them, however I am not sure if system
with CXL support is available in our LAB.

Not sure if I got you right.