kexec/crash: no crash update when kexec in progress

JIRA: https://issues.redhat.com/browse/RHEL-114163

Upstream Status: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit 6efbd5d
Author: Sourabh Jain <sourabhjain@linux.ibm.com>
Date:   Sat Sep 21 16:07:45 2024 +0530

    kexec/crash: no crash update when kexec in progress

    The following errors are observed when kexec is done with SMT=off on
    powerpc.

    [  358.458385] Removing IBM Power 842 compression device
    [  374.795734] kexec_core: Starting new kernel
    [  374.795748] kexec: Waking offline cpu 1.
    [  374.875695] crash hp: kexec_trylock() failed, elfcorehdr may be inaccurate
    [  374.935833] kexec: Waking offline cpu 2.
    [  375.015664] crash hp: kexec_trylock() failed, elfcorehdr may be inaccurate
    snip..
    [  375.515823] kexec: Waking offline cpu 6.
    [  375.635667] crash hp: kexec_trylock() failed, elfcorehdr may be inaccurate
    [  375.695836] kexec: Waking offline cpu 7.

    To avoid kexec kernel boot failure on PowerPC, all the present CPUs that
    are offline are brought online during kexec.  For more information, refer
    to commit e8e5c21 ("powerpc/kexec: Fix orphaned offline CPUs across
    kexec").  Bringing the CPUs online triggers the crash hotplug handler,
    crash_handle_hotplug_event(), to update the kdump image.  Since the system
    is on the kexec kernel boot path and the kexec lock is held, the
    crash_handle_hotplug_event() function fails to acquire the same lock to
    update the kdump image, resulting in the error messages mentioned above.

    To fix this, return from crash_handle_hotplug_event() without printing the
    error message if kexec is in progress.

    The same applies to the crash_check_hotplug_support() function.  Return 0
    if kexec is in progress because kernel is not in a position to update the
    kdump image.

    Link: https://lkml.kernel.org/r/20240921103745.560430-1-sourabhjain@linux.ibm.com
    Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
    Acked-by: Baoquan he <bhe@redhat.com>
    Reported-by: Sachin P Bappalige <sachinpb@linux.vnet.ibm.com>
    Cc: Hari Bathini <hbathini@linux.ibm.com>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Baoquan He <bhe@redhat.com>

Author: Baoquan He

kernel/crash_core.c

@@ -503,7 +503,8 @@ int crash_check_hotplug_support(void)
 	crash_hotplug_lock();
 	/* Obtain lock while reading crash information */
 	if (!kexec_trylock()) {
-		pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
+		if (!kexec_in_progress)
+			pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
 		crash_hotplug_unlock();
 		return 0;
 	}
@@ -545,7 +546,8 @@ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu,
 	crash_hotplug_lock();
 	/* Obtain lock while changing crash information */
 	if (!kexec_trylock()) {
-		pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
+		if (!kexec_in_progress)
+			pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
 		crash_hotplug_unlock();
 		return;
 	}