+ kho-allow-scratch-areas-with-zero-size.patch added to mm-new branch

+ kho-allow-scratch-areas-with-zero-size.patch added to mm-new branch

[Andrew Morton]

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The patch titled
     Subject: kho: allow scratch areas with zero size
has been added to the -mm mm-new branch.  Its filename is
     kho-allow-scratch-areas-with-zero-size.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kho-allow-scratch-areas-with-zero-size.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Subject: kho: allow scratch areas with zero size
Date: Mon, 11 Aug 2025 11:25:08 +0300

Patch series "kho: fixes and cleanups", v3.

These are small KHO and KHO test fixes and cleanups.


This patch (of 3):

Parsing of kho_scratch parameter treats zero size as an invalid value,
although it should be fine for user to request zero sized scratch area for
some types if scratch memory, when for example there is no need to create
scratch area in the low memory.

Treat zero as a valid value for a scratch area size but reject kho_scratch
parameter that defines no scratch memory at all.

Link: https://lkml.kernel.org/r/20250811082510.4154080-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20250811082510.4154080-2-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/kexec_handover.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/kernel/kexec_handover.c~kho-allow-scratch-areas-with-zero-size
+++ a/kernel/kexec_handover.c
@@ -405,6 +405,7 @@ static int __init kho_parse_scratch_size
 {
 	size_t len;
 	unsigned long sizes[3];
+	size_t total_size = 0;
 	int i;
 
 	if (!p)
@@ -441,11 +442,15 @@ static int __init kho_parse_scratch_size
 		}
 
 		sizes[i] = memparse(p, &endp);
-		if (!sizes[i] || endp == p)
+		if (endp == p)
 			return -EINVAL;
 		p = endp;
+		total_size += sizes[i];
 	}
 
+	if (!total_size)
+		return -EINVAL;
+
 	scratch_size_lowmem = sizes[0];
 	scratch_size_global = sizes[1];
 	scratch_size_pernode = sizes[2];
_

Patches currently in -mm which might be from rppt@kernel.org are

kho-allow-scratch-areas-with-zero-size.patch
lib-test_kho-fixes-for-error-handling.patch
selftest-kho-update-generation-of-initrd.patch