From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
Jerome Glisse <jglisse@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
peterx@redhat.com, Martin Cracauer <cracauer@cons.org>,
Matthew Wilcox <willy@infradead.org>, Shaohua Li <shli@fb.com>,
Marty McFadden <mcfadden8@llnl.gov>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v5 09/16] mm: Return faster for non-fatal signals in user mode faults
Date: Thu, 26 Sep 2019 17:38:57 +0800 [thread overview]
Message-ID: <20190926093904.5090-10-peterx@redhat.com> (raw)
In-Reply-To: <20190926093904.5090-1-peterx@redhat.com>
The idea comes from the upstream discussion between Linus and Andrea:
https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/
A summary to the issue: there was a special path in handle_userfault()
in the past that we'll return a VM_FAULT_NOPAGE when we detected
non-fatal signals when waiting for userfault handling. We did that by
reacquiring the mmap_sem before returning. However that brings a risk
in that the vmas might have changed when we retake the mmap_sem and
even we could be holding an invalid vma structure.
This patch is a preparation of removing that special path by allowing
the page fault to return even faster if we were interrupted by a
non-fatal signal during a user-mode page fault handling routine.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
include/linux/sched/signal.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 46429192733b..031af0a6505a 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -387,7 +387,8 @@ static inline bool fault_signal_pending(unsigned int fault_flags,
struct pt_regs *regs)
{
return unlikely((fault_flags & VM_FAULT_RETRY) &&
- fatal_signal_pending(current));
+ (fatal_signal_pending(current) ||
+ (user_mode(regs) && signal_pending(current))));
}
/*
--
2.21.0
next prev parent reply other threads:[~2019-09-26 9:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 9:38 [PATCH v5 00/16] mm: Page fault enhancements Peter Xu
2019-09-26 9:38 ` [PATCH v5 01/16] mm/gup: Rename "nonblocking" to "locked" where proper Peter Xu
2019-09-26 9:38 ` [PATCH v5 02/16] mm/gup: Fix __get_user_pages() on fault retry of hugetlb Peter Xu
2019-09-26 9:38 ` [PATCH v5 03/16] mm: Introduce fault_signal_pending() Peter Xu
2019-09-26 9:38 ` [PATCH v5 04/16] x86/mm: Use helper fault_signal_pending() Peter Xu
2019-09-26 9:38 ` [PATCH v5 05/16] arc/mm: " Peter Xu
2019-09-26 9:38 ` [PATCH v5 06/16] arm64/mm: " Peter Xu
2019-09-26 9:38 ` [PATCH v5 07/16] powerpc/mm: " Peter Xu
2019-09-26 9:38 ` [PATCH v5 08/16] sh/mm: " Peter Xu
2019-09-26 9:38 ` Peter Xu [this message]
2019-09-26 9:38 ` [PATCH v5 10/16] userfaultfd: Don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-09-26 9:38 ` [PATCH v5 11/16] mm: Introduce FAULT_FLAG_DEFAULT Peter Xu
2019-09-26 9:39 ` [PATCH v5 12/16] mm: Introduce FAULT_FLAG_INTERRUPTIBLE Peter Xu
2019-09-26 9:39 ` [PATCH v5 13/16] mm: Allow VM_FAULT_RETRY for multiple times Peter Xu
2019-09-26 9:39 ` [PATCH v5 14/16] mm/gup: " Peter Xu
2019-09-26 9:39 ` [PATCH v5 15/16] mm/gup: Allow to react to fatal signals Peter Xu
2019-09-26 9:39 ` [PATCH v5 16/16] mm/userfaultfd: Honor FAULT_FLAG_KILLABLE in fault path Peter Xu
2019-09-29 9:16 ` Peter Xu
2019-10-14 8:40 ` [PATCH v5 00/16] mm: Page fault enhancements Peter Xu
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