From 71335f37c5e8ec9225285206f7f875057b9737ad Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Wed, 1 Apr 2020 21:08:53 -0700 Subject: 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 Signed-off-by: Andrew Morton Tested-by: Brian Geffon Cc: Andrea Arcangeli Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220160256.9887-1-peterx@redhat.com Signed-off-by: Linus Torvalds --- mm/gup.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'mm/gup.c') diff --git a/mm/gup.c b/mm/gup.c index efe9038933d9..da3e03185144 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 @@ retry: 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); -- cgit v1.2.3