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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hari Bathini <hbathini@linux.ibm.com>,
        David Gibson <dgibson@redhat.com>,
        Dave Young <dyoung@redhat.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 17/94] powerpc/kdump: Handle crashkernel memory reservation failure
Date:   Tue,  2 Oct 2018 06:24:31 -0700
Message-Id: <20181002132501.673653360@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

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

[ Upstream commit 8950329c4a64c6d3ca0bc34711a1afbd9ce05657 ]

Memory reservation for crashkernel could fail if there are holes around
kdump kernel offset (128M). Fail gracefully in such cases and print an
error message.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: David Gibson <dgibson@redhat.com>
Reviewed-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/powerpc/kernel/machine_kexec.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -186,7 +186,12 @@ void __init reserve_crashkernel(void)
 			(unsigned long)(crashk_res.start >> 20),
 			(unsigned long)(memblock_phys_mem_size() >> 20));
 
-	memblock_reserve(crashk_res.start, crash_size);
+	if (!memblock_is_region_memory(crashk_res.start, crash_size) ||
+	    memblock_reserve(crashk_res.start, crash_size)) {
+		pr_err("Failed to reserve memory for crashkernel!\n");
+		crashk_res.start = crashk_res.end = 0;
+		return;
+	}
 }
 
 int overlaps_crashkernel(unsigned long start, unsigned long size)