Re: [PATCH] resource,kexec: walk_system_ram_res_rev must retain resource flags

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Thu, Oct 17, 2024 at 03:03:47PM -0400, 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.
> 
> This leads to undefined behavior after reboot. If the kexec buffer
> is never touched, nothing happens. If the kexec buffer is touched,
> it could lead to a crash (like below) or undefined behavior.
> 
> Tested on a system with CXL memory expanders with driver managed
> memory, TPM enabled, and CONFIG_IMA_KEXEC=y. Adding printk's
> showed the flags were being discarded and as a result the check
> for IORESOURCE_SYSRAM_DRIVER_MANAGED passes.
> 
> find_next_iomem_res: name(System RAM (kmem))
> 		     start(10000000000)
> 		     end(1034fffffff)
> 		     flags(83000200)
> 
> locate_mem_hole_top_down: start(10000000000) end(1034fffffff) flags(0)
> 
> [.] BUG: unable to handle page fault for address: ffff89834ffff000

Please, cut this down to only important ~3-5 lines as suggested in
the Submitting Patches documentation.

Yeah, I see that Andrew applied it to hist testing branch, if it's not going to
be updated there, consider above as a hint for the future contributions with
backtraces.

-- 
With Best Regards,
Andy Shevchenko