From 71335f37c5e8ec9225285206f7f875057b9737ad Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 1 Apr 2020 21:08:53 -0700
Subject: [PATCH] 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>
---
mm/gup.c | 12 +++++++++---
mm/hugetlb.c | 3 ++-
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index efe9038933d96..da3e031851443 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -864,7 +864,7 @@ 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) {
@@ -1207,7 +1207,7 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
address = untagged_addr(address);
if (unlocked)
- fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+ fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
retry:
vma = find_extend_vma(mm, address);
@@ -1329,7 +1329,13 @@ 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 0b15dc29e5298..249c92917eb40 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4344,7 +4344,8 @@ 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;
--
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