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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.

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>
This commit is contained in:
Peter Xu 2020-04-01 21:09:00 -07:00 committed by Linus Torvalds
parent 71335f37c5
commit 3e69ad081c
1 changed files with 28 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
fs/userfaultfd.c
View File

@ -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();
}