[RHEL8,COMMIT] mm/gup: allow to react to fatal signals

Submitted by Konstantin Khorenko on April 20, 2020, 7:34 a.m.

Details

Message ID 202004200734.03K7YOgY016164@finist_co8.work.ct
State New
Series "Series without cover letter"
Headers show

Commit Message

Konstantin Khorenko April 20, 2020, 7:34 a.m.
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 16f743d9a59c9505b2166b2d463e145409abba23
Author: Peter Xu <peterx@redhat.com>
Date:   Mon Apr 20 10:34:24 2020 +0300

    mm/gup: allow to react to fatal signals
    
    The existing gup code does not react to the fatal signals in many code
    paths.  For example, in one retry path of gup we're still using
    down_read() rather than down_read_killable().  Also, when doing page
    faults we don't pass in FAULT_FLAG_KILLABLE as well, which means that
    within the faulting process we'll wait in non-killable way as well.  These
    were spotted by Linus during the code review of some other patches.
    
    Let's allow the gup code to react to fatal signals to improve the
    responsiveness of threads when during gup and being killed.
    
    Signed-off-by: Peter Xu <peterx@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Tested-by: Brian Geffon <bgeffon@google.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Bobby Powers <bobbypowers@gmail.com>
    Cc: David Hildenbrand <david@redhat.com>
    Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
    Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Jerome Glisse <jglisse@redhat.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
    Cc: Martin Cracauer <cracauer@cons.org>
    Cc: Marty McFadden <mcfadden8@llnl.gov>
    Cc: Matthew Wilcox <willy@infradead.org>
    Cc: Maya Gokhale <gokhale2@llnl.gov>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Mike Kravetz <mike.kravetz@oracle.com>
    Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
    Cc: Pavel Emelyanov <xemul@openvz.org>
    Link: http://lkml.kernel.org/r/20200220160256.9887-1-peterx@redhat.com
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-102938
    (cherry picked from commit 71335f37c5e8ec9225285206f7f875057b9737ad)
    Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 mm/gup.c     | 12 +++++++++---
 mm/hugetlb.c |  3 ++-
 2 files changed, 11 insertions(+), 4 deletions(-)

Patch hide | download patch | download mbox

diff --git a/mm/gup.c b/mm/gup.c
index cdf438ea8621..3d08b68c210f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -507,7 +507,7 @@  static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 	if (*flags & FOLL_REMOTE)
 		fault_flags |= FAULT_FLAG_REMOTE;
 	if (locked)
-		fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 	if (*flags & FOLL_NOWAIT)
 		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
 	if (*flags & FOLL_TRIED) {
@@ -832,7 +832,7 @@  int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
 	int ret, major = 0;
 
 	if (unlocked)
-		fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 retry:
 	vma = find_extend_vma(mm, address);
@@ -945,7 +945,13 @@  static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 			break;
 
 		*locked = 1;
-		down_read(&mm->mmap_sem);
+		ret = down_read_killable(&mm->mmap_sem);
+		if (ret) {
+			BUG_ON(ret > 0);
+			if (!pages_done)
+				pages_done = ret;
+			break;
+		}
 
 		ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
 				       pages, NULL, locked);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 417b96f4aa14..ec839cd22a3f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4223,7 +4223,8 @@  long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 			if (flags & FOLL_WRITE)
 				fault_flags |= FAULT_FLAG_WRITE;
 			if (locked)
-				fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
+					FAULT_FLAG_KILLABLE;
 			if (flags & FOLL_NOWAIT)
 				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
 					FAULT_FLAG_RETRY_NOWAIT;