mm/userfaultfd: honor FAULT_FLAG_KILLABLE in fault path (3e69ad08) · Commits · 戴 / test

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. 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/20200220160300.9941-1-peterx@redhat.com Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/userfaultfd.c

+28 −8

Original line number	Diff line number	Diff line
		@@ -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_fault *vmf, unsigned long reason)
		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_fault *vmf, unsigned long reason)
		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_fault *vmf, unsigned long reason)
		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_fault *vmf, unsigned long reason)
		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();
		}

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