[Devel] [PATCH RHEL8 COMMIT] arm64/mm: use helper fault_signal_pending()

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.6
------>
commit 2587b246ab7e18819805a5d8c3f856df9dbe7615
Author: Peter Xu <peterx at redhat.com>
Date:   Mon Apr 20 10:34:11 2020 +0300

    arm64/mm: use helper fault_signal_pending()
    
    Let the arm64 fault handling to use the new fault_signal_pending() helper,
    by moving the signal handling out of the retry logic.
    
    Signed-off-by: Peter Xu <peterx at redhat.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Tested-by: Brian Geffon <bgeffon at google.com>
    Cc: Andrea Arcangeli <aarcange at redhat.com>
    Cc: Bobby Powers <bobbypowers at gmail.com>
    Cc: David Hildenbrand <david at redhat.com>
    Cc: Denis Plotnikov <dplotnikov at virtuozzo.com>
    Cc: "Dr . David Alan Gilbert" <dgilbert at redhat.com>
    Cc: Hugh Dickins <hughd at google.com>
    Cc: Jerome Glisse <jglisse at redhat.com>
    Cc: Johannes Weiner <hannes at cmpxchg.org>
    Cc: "Kirill A . Shutemov" <kirill at shutemov.name>
    Cc: Martin Cracauer <cracauer at cons.org>
    Cc: Marty McFadden <mcfadden8 at llnl.gov>
    Cc: Matthew Wilcox <willy at infradead.org>
    Cc: Maya Gokhale <gokhale2 at llnl.gov>
    Cc: Mel Gorman <mgorman at suse.de>
    Cc: Mike Kravetz <mike.kravetz at oracle.com>
    Cc: Mike Rapoport <rppt at linux.vnet.ibm.com>
    Cc: Pavel Emelyanov <xemul at openvz.org>
    Link: http://lkml.kernel.org/r/20200220155927.9264-1-peterx@redhat.com
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-102938
    (cherry picked from commit b502f038f2ffc97a60fefcc120a868aa46009060)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 arch/arm64/mm/fault.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 579c1d88f3f9..61baf230c4a6 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -496,19 +496,14 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 	fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
 	major |= fault & VM_FAULT_MAJOR;
 
-	if (fault & VM_FAULT_RETRY) {
-		/*
-		 * If we need to retry but a fatal signal is pending,
-		 * handle the signal first. We do not need to release
-		 * the mmap_sem because it would already be released
-		 * in __lock_page_or_retry in mm/filemap.c.
-		 */
-		if (fatal_signal_pending(current)) {
-			if (!user_mode(regs))
-				goto no_context;
-			return 0;
-		}
+	/* Quick path to respond to signals */
+	if (fault_signal_pending(fault, regs)) {
+		if (!user_mode(regs))
+			goto no_context;
+		return 0;
+	}
 
+	if (fault & VM_FAULT_RETRY) {
 		/*
 		 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
 		 * starvation.