Re: [PATCH v2 1/2] kexec: Add KEXEC_FILE_NO_CMA as a legal flag

On 08/20/25 at 09:47pm, Andrew Morton wrote:

On Tue, 5 Aug 2025 14:15:26 -0700 Brian Mak [off-list ref] wrote:

quoted

Commit 07d24902977e ("kexec: enable CMA based contiguous allocation")
introduces logic to use CMA-based allocation in kexec by default. As
part of the changes, it introduces a kexec_file_load flag to disable the
use of CMA allocations from userspace. However, this flag is broken
since it is missing from the list of legal flags for kexec_file_load.
kexec_file_load returns EINVAL when attempting to use the flag.

Fix this by adding the KEXEC_FILE_NO_CMA flag to the list of legal flags
for kexec_file_load.

Fixes: 07d24902977e ("kexec: enable CMA based contiguous allocation")

A description of the userspace-visible runtime effects of this bug
would be very helpful, please.  A lot more than "is broken"!

Also, could we please have some reviewer input on this change?

I didn't receive this patchset, and kexec mailing list is not in CC.
I don't know what happened.

quoted

--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h

@@ -460,7 +460,8 @@ bool kexec_load_permitted(int kexec_image_type);
 
 /* List of defined/legal kexec file flags */
 #define KEXEC_FILE_FLAGS	(KEXEC_FILE_UNLOAD | KEXEC_FILE_ON_CRASH | \
-				 KEXEC_FILE_NO_INITRAMFS | KEXEC_FILE_DEBUG)
+				 KEXEC_FILE_NO_INITRAMFS | KEXEC_FILE_DEBUG | \
+				 KEXEC_FILE_NO_CMA)
 
 /* flag to track if kexec reboot is in progress */
 extern bool kexec_in_progress;

-- 
2.25.1