From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Peter Xu <peterx@redhat.com>, Martin Cracauer <cracauer@cons.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Hugh Dickins <hughd@google.com>,
Jerome Glisse <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Brian Geffon <bgeffon@google.com>,
Maya Gokhale <gokhale2@llnl.gov>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Marty McFadden <mcfadden8@llnl.gov>,
David Hildenbrand <david@redhat.com>,
Bobby Powers <bobbypowers@gmail.com>,
Mel Gorman <mgorman@suse.de>
Subject: [PATCH RESEND v6 09/16] mm: Return faster for non-fatal signals in user mode faults
Date: Thu, 20 Feb 2020 11:02:30 -0500 [thread overview]
Message-ID: <20200220160230.9598-1-peterx@redhat.com> (raw)
In-Reply-To: <20200220155353.8676-1-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 4c87ffce64d1..09d40ce6a162 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -379,7 +379,8 @@ 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))));
}
/*
--
2.24.1
next prev parent reply other threads:[~2020-02-20 16:02 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 15:53 [PATCH RESEND v6 00/16] mm: Page fault enhancements Peter Xu
2020-02-20 15:53 ` [PATCH RESEND v6 01/16] mm/gup: Rename "nonblocking" to "locked" where proper Peter Xu
2020-02-20 15:53 ` [PATCH RESEND v6 02/16] mm/gup: Fix __get_user_pages() on fault retry of hugetlb Peter Xu
2020-03-02 19:02 ` David Hildenbrand
2020-03-02 20:07 ` Peter Xu
2020-03-02 20:22 ` David Hildenbrand
2020-02-20 15:53 ` [PATCH RESEND v6 03/16] mm: Introduce fault_signal_pending() Peter Xu
2020-03-02 19:04 ` David Hildenbrand
2020-02-20 15:53 ` [PATCH RESEND v6 04/16] x86/mm: Use helper fault_signal_pending() Peter Xu
2020-02-20 15:58 ` [PATCH RESEND v6 05/16] arc/mm: " Peter Xu
2020-02-20 15:59 ` [PATCH RESEND v6 06/16] arm64/mm: " Peter Xu
2020-02-20 16:02 ` [PATCH RESEND v6 07/16] powerpc/mm: " Peter Xu
2020-02-20 16:02 ` [PATCH RESEND v6 08/16] sh/mm: " Peter Xu
2020-02-20 16:02 ` Peter Xu [this message]
2020-02-20 16:02 ` [PATCH RESEND v6 10/16] userfaultfd: Don't retake mmap_sem to emulate NOPAGE Peter Xu
2020-02-20 16:02 ` [PATCH RESEND v6 11/16] mm: Introduce FAULT_FLAG_DEFAULT Peter Xu
2020-02-20 16:02 ` [PATCH RESEND v6 13/16] mm: Allow VM_FAULT_RETRY for multiple times Peter Xu
2020-02-20 16:02 ` [PATCH RESEND v6 15/16] mm/gup: Allow to react to fatal signals Peter Xu
2020-02-20 16:03 ` [PATCH RESEND v6 16/16] mm/userfaultfd: Honor FAULT_FLAG_KILLABLE in fault path Peter Xu
2020-02-20 19:53 ` [PATCH RESEND v6 12/16] mm: Introduce FAULT_FLAG_INTERRUPTIBLE Peter Xu
2020-02-20 19:53 ` [PATCH RESEND v6 14/16] mm/gup: Allow VM_FAULT_RETRY for multiple times Peter Xu
2020-02-21 19:26 ` [PATCH RESEND v6 00/16] mm: Page fault enhancements Brian Geffon
2020-03-02 17:31 ` Peter Xu
2020-02-21 19:32 ` Linus Torvalds
2020-02-21 20:11 ` Peter Xu
2020-03-07 20:33 ` David Hildenbrand
2020-03-07 21:47 ` Peter Xu
2020-03-08 12:12 ` David Hildenbrand
2020-03-09 19:51 ` Peter Xu
2020-03-09 20:06 ` David Hildenbrand
2020-03-08 12:49 ` David Hildenbrand
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