+ riscv-keep-booting-if-kfence-pool-reservation-fails.patch added to mm-new branch

+ riscv-keep-booting-if-kfence-pool-reservation-fails.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: riscv: keep booting if KFENCE pool reservation fails
has been added to the -mm mm-new branch.  Its filename is
     riscv-keep-booting-if-kfence-pool-reservation-fails.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/riscv-keep-booting-if-kfence-pool-reservation-fails.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
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
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and is updated there most days

------------------------------------------------------
From: Jackie Liu <liuyun01@kylinos.cn>
Subject: riscv: keep booting if KFENCE pool reservation fails
Date: Thu, 29 Oct 2026 10:57:43 +0800

A failed KFENCE pool reservation hits BUG_ON() and stops boot. Continue
building the linear map and disable KFENCE if the reservation fails.

Reject later pool initialization as well, since a replacement pool may
have huge-page mappings that kfence_protect_page() cannot handle.

Link: https://lore.kernel.org/44fbd039a5cd78bfe7355ccbafb197775dede29c.1793242457.git.liuyun01@kylinos.cn
Fixes: 25abe0db9243 ("riscv: Fix kfence now that the linear mapping can be backed by PUD/P4D/PGD")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/cover.1793017073.git.liuyun01@kylinos.cn?part=3
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202610290904.wbrEL97y-lkp@intel.com/
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: AlexandreGhiti <alex@ghiti.fr>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
---

 arch/riscv/include/asm/kfence.h |    4 +++-
 arch/riscv/mm/init.c            |   18 ++++++++++++++----
 2 files changed, 17 insertions(+), 5 deletions(-)

--- a/arch/riscv/include/asm/kfence.h~riscv-keep-booting-if-kfence-pool-reservation-fails
+++ a/arch/riscv/include/asm/kfence.h
@@ -9,9 +9,11 @@
 #include <asm/cacheflush.h>
 #include <asm/pgtable.h>
 
+extern bool kfence_disabled;
+
 static inline bool arch_kfence_init_pool(void)
 {
-	return true;
+	return !kfence_disabled;
 }
 
 static inline bool kfence_protect_page(unsigned long addr, bool protect)
--- a/arch/riscv/mm/init.c~riscv-keep-booting-if-kfence-pool-reservation-fails
+++ a/arch/riscv/mm/init.c
@@ -45,6 +45,10 @@ DECLARE_BITMAP(new_valid_map_cpus, NR_CP
 struct kernel_mapping kernel_map __ro_after_init;
 EXPORT_SYMBOL(kernel_map);
 
+#ifdef CONFIG_KFENCE
+bool kfence_disabled __ro_after_init;
+#endif
+
 #ifdef CONFIG_64BIT
 u64 satp_mode __ro_after_init = SATP_MODE_57;
 #else
@@ -1230,10 +1234,13 @@ static void __init create_linear_mapping
 	 *  for this region.
 	 */
 	kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE);
-	BUG_ON(!kfence_pool);
-
-	memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
-	__kfence_pool = __va(kfence_pool);
+	if (kfence_pool) {
+		memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
+		__kfence_pool = __va(kfence_pool);
+	} else {
+		pr_err("failed to allocate kfence pool\n");
+		kfence_disabled = true;
+	}
 #endif
 
 	/* Map all memory banks in the linear mapping */
@@ -1254,6 +1261,9 @@ static void __init create_linear_mapping
 #endif
 
 #ifdef CONFIG_KFENCE
+	if (!kfence_pool)
+		return;
+
 	create_linear_mapping_range(kfence_pool, kfence_pool + KFENCE_POOL_SIZE, PAGE_SIZE, NULL);
 
 	memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
_

Patches currently in -mm which might be from liuyun01@kylinos.cn are

kfence-fix-pool-cleanup-on-metadata-allocation-failure.patch
kfence-clear-the-pool-pointer-before-freeing-pages.patch
riscv-keep-booting-if-kfence-pool-reservation-fails.patch