On 04/22/2018 07:28 AM, Nicholas Piggin wrote:

On Fri, 20 Apr 2018 10:34:35 +0530
Mahesh J Salgaonkar [off-list ref] wrote:

quoted

From: Mahesh Salgaonkar <redacted>

otherwise the fadump registration in new kexec-ed kernel complains that
fadump is already registered. This makes new kernel to continue using
fadump registered by previous kernel which may lead to invalid vmcore
generation. Hence this patch fixes this issue by un-registering fadump
in fadump_cleanup() which is called during kexec path so that new kernel
can register fadump with new valid values.

Is this a bug fix that should go to previous kernels as well?

Yes.

quoted

Signed-off-by: Mahesh Salgaonkar <redacted>
---
 arch/powerpc/kernel/fadump.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 43bfa535d0ea..16b3e8c5cae0 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c

@@ -1276,6 +1276,9 @@ void fadump_cleanup(void)
 	/* Invalidate the registration only if dump is active. */
 	if (fw_dump.dump_active) {
 		fadump_invalidate_dump(fdm_active);
+	} else if (fw_dump.dump_registered) {
+		/* Un-register Firmware-assisted dump if it was registered. */
+		fadump_unregister_dump(&fdm);
 	}
 }