Commit 8597538712eb ("powerpc/fadump: Do not use hugepages when fadump
is active") disabled hugetlb support when fadump is active by returning
early from hugetlbpage_init():arch/powerpc/mm/hugetlbpage.c and not
populating hpage_shift/HPAGE_SHIFT.
Later, commit 2354ad252b66 ("powerpc/mm: Update default hugetlb size
early") moved the allocation of hpage_shift/HPAGE_SHIFT to early boot,
which inadvertently re-enabled hugetlb support when fadump is active.
Fix this by implementing hugepages_supported() on powerpc. This ensures
that disabling hugetlb for the fadump kernel is independent of
hpage_shift/HPAGE_SHIFT.
Fixes: 2354ad252b66 ("powerpc/mm: Update default hugetlb size early")
CC: Aneesh Kumar K.V <aneesh.ku...@kernel.org>
CC: Hari Bathini <hbath...@linux.ibm.com>
CC: Madhavan Srinivasan <ma...@linux.ibm.com>
Cc: Mahesh Salgaonkar <mah...@linux.ibm.com>
Cc: Michael Ellerman <m...@ellerman.id.au>
CC: Ritesh Harjani (IBM) <ritesh.l...@gmail.com>
Signed-off-by: Sourabh Jain <sourabhj...@linux.ibm.com>
---
Note: Even with this fix included, it is possible to enable gigantic
pages in the fadump kernel. IIUC, gigantic pages were never disabled
for the fadump kernel.
Currently, gigantic pages are allocated during early boot as long as
the respective hstate is supported by the architecture.
I will introduce some changes in the generic hugetlb code to allow the
architecture to decide on supporting gigantic pages on the go. Bringing
gigantic page allocation under hugepages_supported() does work for
powerpc but I need verify the impact on other architectures.
Regarding the Fixes tag: This patch fixes a bug inadvertently introduced
by the commit mentioned under Fixes tag in the commit message. Feel free
to remove the tag if it is unnecessary.
---
arch/powerpc/include/asm/hugetlb.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/include/asm/hugetlb.h
b/arch/powerpc/include/asm/hugetlb.h
index 18a3028ac3b6..f294e57663b0 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -15,6 +15,15 @@
extern bool hugetlb_disabled;
+static inline int hugepages_supported(void)
+{
+ if (hugetlb_disabled)
+ return 0;
+
+ return HPAGE_SHIFT != 0;
+}
+#define hugepages_supported hugepages_supported
+
void __init hugetlbpage_init_defaultsize(void);
int slice_is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
--
2.47.0
