From: Oleg Nesterov <oleg@redhat.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>,
linux-mm <linux-mm@kvack.org>, Peter Xu <peterx@redhat.com>,
Mike Rapoport <rppt@linux.ibm.com>, Jann Horn <jannh@google.com>,
Jason Gunthorpe <jgg@mellanox.com>,
Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [BUG] kernel BUG at fs/userfaultfd.c:385 after 04f5866e41fb
Date: Wed, 28 Aug 2019 16:25:45 +0200 [thread overview]
Message-ID: <20190828142544.GB3721@redhat.com> (raw)
In-Reply-To: <20190827171410.GB4823@redhat.com>
On 08/27, Andrea Arcangeli wrote:
>
> I finished the debugging of the ioctl refcounting last week, but I
> didn't yet post an update sorry.
Great! so we can finally forget this problem ;)
> It was important to verify the uffd ctx of the UFFDIO_COPY ioctl is
> different than the one registered on the vma where UFFDIO_COPY hits
> handle_userfault,
I seem to understand... Somehow I thought that __mcopy_atomic() should
verify that dst_vma->vm_userfaultfd_ctx.ctx is the same ctx which was
used in userfaultfd_ioctl() but it doesn't, it only checks
dst_vma->vm_userfaultfd_ctx.ctx != NULL.
But why?
(I am just curious, let me repeat I know nothing about userfaultfd).
Oleg.
next prev parent reply other threads:[~2019-08-28 14:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 9:08 Kefeng Wang
2019-08-14 13:53 ` Michal Hocko
2019-08-14 14:45 ` Kefeng Wang
2019-08-14 15:10 ` Oleg Nesterov
2019-08-14 15:41 ` Oleg Nesterov
2019-08-15 2:21 ` Kefeng Wang
2019-08-15 9:54 ` Oleg Nesterov
2019-08-16 10:37 ` Kefeng Wang
2019-08-19 12:48 ` Oleg Nesterov
2019-08-19 16:05 ` Andrea Arcangeli
2019-08-20 15:59 ` Oleg Nesterov
2019-08-20 16:15 ` Andrea Arcangeli
[not found] ` <73d7b5b1-a88c-5fca-ba16-be214c2524a4@I-love.SAKURA.ne.jp>
2019-08-20 16:09 ` Oleg Nesterov
2019-08-20 16:02 ` [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx Oleg Nesterov
2019-08-20 16:05 ` Andrea Arcangeli
2019-08-21 0:53 ` Kefeng Wang
2019-08-27 16:33 ` [BUG] kernel BUG at fs/userfaultfd.c:385 after 04f5866e41fb Oleg Nesterov
2019-08-27 17:14 ` Andrea Arcangeli
2019-08-28 14:25 ` Oleg Nesterov [this message]
2019-08-29 12:05 ` Andrea Arcangeli
2019-08-30 16:49 ` Oleg Nesterov
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