The patch titled
Subject: mm/gup: allow to react to fatal signals
has been added to the -mm tree. Its filename is
mm-gup-allow-to-react-to-fatal-signals.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-allow-to-react-to-fatal-signals.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-allow-to-react-to-fatal-signals.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
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.
Link: http://lkml.kernel.org/r/20200220160256.9887-1-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Bobby Powers <bobbypowers@xxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Denis Plotnikov <dplotnikov@xxxxxxxxxxxxx>
Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: "Kirill A . Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Martin Cracauer <cracauer@xxxxxxxx>
Cc: Marty McFadden <mcfadden8@xxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Maya Gokhale <gokhale2@xxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 12 +++++++++---
mm/hugetlb.c | 3 ++-
2 files changed, 11 insertions(+), 4 deletions(-)
--- a/mm/gup.c~mm-gup-allow-to-react-to-fatal-signals
+++ a/mm/gup.c
@@ -857,7 +857,7 @@ static int faultin_page(struct task_stru
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) {
@@ -1200,7 +1200,7 @@ int fixup_user_fault(struct task_struct
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);
@@ -1322,7 +1322,13 @@ 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);
--- a/mm/hugetlb.c~mm-gup-allow-to-react-to-fatal-signals
+++ a/mm/hugetlb.c
@@ -4344,7 +4344,8 @@ long follow_hugetlb_page(struct mm_struc
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;
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-gup-rename-nonblocking-to-locked-where-proper.patch
mm-gup-fix-__get_user_pages-on-fault-retry-of-hugetlb.patch
mm-introduce-fault_signal_pending.patch
x86-mm-use-helper-fault_signal_pending.patch
arc-mm-use-helper-fault_signal_pending.patch
arm64-mm-use-helper-fault_signal_pending.patch
powerpc-mm-use-helper-fault_signal_pending.patch
sh-mm-use-helper-fault_signal_pending.patch
mm-return-faster-for-non-fatal-signals-in-user-mode-faults.patch
userfaultfd-dont-retake-mmap_sem-to-emulate-nopage.patch
mm-introduce-fault_flag_default.patch
mm-introduce-fault_flag_interruptible.patch
mm-allow-vm_fault_retry-for-multiple-times.patch
mm-gup-allow-vm_fault_retry-for-multiple-times.patch
mm-gup-allow-to-react-to-fatal-signals.patch
mm-userfaultfd-honor-fault_flag_killable-in-fault-path.patch
mm-merge-parameters-for-change_protection.patch
userfaultfd-wp-apply-_page_uffd_wp-bit.patch
userfaultfd-wp-drop-_page_uffd_wp-properly-when-fork.patch
userfaultfd-wp-add-pmd_swp_uffd_wp-helpers.patch
userfaultfd-wp-support-swap-and-page-migration.patch
khugepaged-skip-collapse-if-uffd-wp-detected.patch
userfaultfd-wp-dont-wake-up-when-doing-write-protect.patch
userfaultfd-wp-declare-_uffdio_writeprotect-conditionally.patch
userfaultfd-selftests-refactor-statistics.patch
userfaultfd-selftests-add-write-protect-test.patch
