[PATCH rebased 1/2] powerpc: reserve memory for capture kernel after hugepages init

[Michal Suchanek]

From: Hari Bathini <hbathini at linux.ibm.com>

Sometimes, memory reservation for KDump/FADump can overlap with memory
marked for hugepages. This overlap leads to error, hang in KDump case
and copy error reported by f/w in case of FADump, while trying to
capture dump. Report error while setting up memory for the capture
kernel instead of running into issues while capturing dump, by moving
KDump/FADump reservation below MMU early init and failing gracefully
when hugepages memory overlaps with capture kernel memory.

Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
---
 arch/powerpc/kernel/prom.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 6620f37abe73..0f14dc9c4dab 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -735,14 +735,6 @@ void __init early_init_devtree(void *params)
 	if (PHYSICAL_START > MEMORY_START)
 		memblock_reserve(MEMORY_START, 0x8000);
 	reserve_kdump_trampoline();
-#if defined(CONFIG_FA_DUMP) || defined(CONFIG_PRESERVE_FA_DUMP)
-	/*
-	 * If we fail to reserve memory for firmware-assisted dump then
-	 * fallback to kexec based kdump.
-	 */
-	if (fadump_reserve_mem() == 0)
-#endif
-		reserve_crashkernel();
 	early_reserve_mem();
 
 	/* Ensure that total memory size is page-aligned. */
@@ -781,6 +773,14 @@ void __init early_init_devtree(void *params)
 #endif
 
 	mmu_early_init_devtree();
+#if defined(CONFIG_FA_DUMP) || defined(CONFIG_PRESERVE_FA_DUMP)
+	/*
+	 * If we fail to reserve memory for firmware-assisted dump then
+	 * fallback to kexec based kdump.
+	 */
+	if (fadump_reserve_mem() == 0)
+#endif
+		reserve_crashkernel();
 
 #ifdef CONFIG_PPC_POWERNV
 	/* Scan and build the list of machine check recoverable ranges */
-- 
2.23.0