The patch titled
Subject: mm/userfaultfd: honor FAULT_FLAG_KILLABLE in fault path
has been added to the -mm tree. Its filename is
mm-userfaultfd-honor-fault_flag_killable-in-fault-path.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-userfaultfd-honor-fault_flag_killable-in-fault-path.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-userfaultfd-honor-fault_flag_killable-in-fault-path.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/userfaultfd: honor FAULT_FLAG_KILLABLE in fault path
Userfaultfd fault path was by default killable even if the caller does not
have FAULT_FLAG_KILLABLE. That makes sense before in that when with gup
we don't have FAULT_FLAG_KILLABLE properly set before. Now after previous
patch we've got FAULT_FLAG_KILLABLE applied even for gup code so it should
also make sense to let userfaultfd to honor the FAULT_FLAG_KILLABLE.
Because we're unconditionally setting FAULT_FLAG_KILLABLE in gup code
right now, this patch should have no functional change. It also cleaned
the code a little bit by introducing some helpers.
Link: http://lkml.kernel.org/r/20200220160300.9941-1-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>
---
fs/userfaultfd.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
--- a/fs/userfaultfd.c~mm-userfaultfd-honor-fault_flag_killable-in-fault-path
+++ a/fs/userfaultfd.c
@@ -334,6 +334,30 @@ out:
return ret;
}
+/* Should pair with userfaultfd_signal_pending() */
+static inline long userfaultfd_get_blocking_state(unsigned int flags)
+{
+ if (flags & FAULT_FLAG_INTERRUPTIBLE)
+ return TASK_INTERRUPTIBLE;
+
+ if (flags & FAULT_FLAG_KILLABLE)
+ return TASK_KILLABLE;
+
+ return TASK_UNINTERRUPTIBLE;
+}
+
+/* Should pair with userfaultfd_get_blocking_state() */
+static inline bool userfaultfd_signal_pending(unsigned int flags)
+{
+ if (flags & FAULT_FLAG_INTERRUPTIBLE)
+ return signal_pending(current);
+
+ if (flags & FAULT_FLAG_KILLABLE)
+ return fatal_signal_pending(current);
+
+ return false;
+}
+
/*
* The locking rules involved in returning VM_FAULT_RETRY depending on
* FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and
@@ -355,7 +379,7 @@ vm_fault_t handle_userfault(struct vm_fa
struct userfaultfd_ctx *ctx;
struct userfaultfd_wait_queue uwq;
vm_fault_t ret = VM_FAULT_SIGBUS;
- bool must_wait, return_to_userland;
+ bool must_wait;
long blocking_state;
/*
@@ -462,9 +486,7 @@ vm_fault_t handle_userfault(struct vm_fa
uwq.ctx = ctx;
uwq.waken = false;
- return_to_userland = vmf->flags & FAULT_FLAG_INTERRUPTIBLE;
- blocking_state = return_to_userland ? TASK_INTERRUPTIBLE :
- TASK_KILLABLE;
+ blocking_state = userfaultfd_get_blocking_state(vmf->flags);
spin_lock_irq(&ctx->fault_pending_wqh.lock);
/*
@@ -490,8 +512,7 @@ vm_fault_t handle_userfault(struct vm_fa
up_read(&mm->mmap_sem);
if (likely(must_wait && !READ_ONCE(ctx->released) &&
- (return_to_userland ? !signal_pending(current) :
- !fatal_signal_pending(current)))) {
+ !userfaultfd_signal_pending(vmf->flags))) {
wake_up_poll(&ctx->fd_wqh, EPOLLIN);
schedule();
ret |= VM_FAULT_MAJOR;
@@ -513,8 +534,7 @@ vm_fault_t handle_userfault(struct vm_fa
set_current_state(blocking_state);
if (READ_ONCE(uwq.waken) ||
READ_ONCE(ctx->released) ||
- (return_to_userland ? signal_pending(current) :
- fatal_signal_pending(current)))
+ userfaultfd_signal_pending(vmf->flags))
break;
schedule();
}
_
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
