powerpc/fadump: Do not use hugepages when fadump is active

FADump capture kernel boots in restricted memory environment preserving
the context of previous kernel to save vmcore. Supporting hugepages in
such environment makes things unnecessarily complicated, as hugepages
need memory set aside for them. This means most of the capture kernel's
memory is used in supporting hugepages. In most cases, this results in
out-of-memory issues while booting FADump capture kernel. But hugepages
are not of much use in capture kernel whose only job is to save vmcore.
So, disabling hugepages support, when fadump is active, is a reliable
solution for the out of memory issues. Introducing a flag variable to
disable HugeTLB support when fadump is active.

Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 0bd3790d35df..5beeec6fbb9b 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -572,8 +572,10 @@ static void __init htab_scan_page_sizes(void)
 	}
 
 #ifdef CONFIG_HUGETLB_PAGE
-	/* Reserve 16G huge page memory sections for huge pages */
-	of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
+	if (!hugetlb_disabled) {
+		/* Reserve 16G huge page memory sections for huge pages */
+		of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
+	}
 #endif /* CONFIG_HUGETLB_PAGE */
 }