From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
qemu-devel@nongnu.org, linux-mm@kvack.org
Subject: [Qemu-devel] [PATCH 0/1] FOLL_NOWAIT and get_user_pages_unlocked
Date: Fri, 2 Mar 2018 18:43:42 +0100 [thread overview]
Message-ID: <20180302174343.5421-1-aarcange@redhat.com> (raw)
Hello,
KVM is hanging on postcopy live migration.
David tracked it down to commit
ce53053ce378c21e7ffc45241fd67d6ee79daa2b and the problem is pretty
obvious then.
Either we teach get_user_pages_locked/unlocked to handle FOLL_NOWAIT
(so faultin_nopage works right even when the nonblocking pointer is
not NULL) or we need to revert part of commit
ce53053ce378c21e7ffc45241fd67d6ee79daa2b and keep using FOLL_NOWAIT
only as parameter to get_user_pages (which won't ever set nonblocking
pointer to non-NULL). I suppose the former approach is preferred to be
more robust.
Thanks,
Andrea
Andrea Arcangeli (1):
mm: gup: teach get_user_pages_unlocked to handle FOLL_NOWAIT
mm/gup.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
next reply other threads:[~2018-03-02 17:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-02 17:43 Andrea Arcangeli [this message]
2018-03-02 17:43 ` [Qemu-devel] [PATCH 1/1] mm: gup: teach get_user_pages_unlocked to handle FOLL_NOWAIT Andrea Arcangeli
2018-03-02 19:39 ` Andrew Morton
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