From: Peter Xu <peterx@redhat.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com,
lokeshgidra@google.com, david@redhat.com, ryan.roberts@arm.com,
hughd@google.com, mhocko@suse.com, axelrasmussen@google.com,
rppt@kernel.org, willy@infradead.org, Liam.Howlett@oracle.com,
jannh@google.com, zhangpeng362@huawei.com, bgeffon@google.com,
kaleshsingh@google.com, ngeoffray@google.com, jdduke@google.com,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
kernel-team@android.com
Subject: Re: [PATCH v2 1/1] userfaultfd: fix move_pages_pte() splitting folio under RCU read lock
Date: Wed, 3 Jan 2024 09:54:58 +0800 [thread overview]
Message-ID: <ZZS-crdr54WqL7Ns@x1n> (raw)
In-Reply-To: <20240102233256.1077959-1-surenb@google.com>
On Tue, Jan 02, 2024 at 03:32:56PM -0800, Suren Baghdasaryan wrote:
> While testing the split PMD path with lockdep enabled I've got an
> "Invalid wait context" error caused by split_huge_page_to_list() trying
> to lock anon_vma->rwsem while inside RCU read section. The issues is due
> to move_pages_pte() calling split_folio() under RCU read lock. Fix this
> by unmapping the PTEs and exiting RCU read section before splitting the
> folio and then retrying. The same retry pattern is used when locking the
> folio or anon_vma in this function. After splitting the large folio we
> unlock and release it because after the split the old folio might not be
> the one that contains the src_addr.
>
> Fixes: 94b01c885131 ("userfaultfd: UFFDIO_MOVE uABI")
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks,
--
Peter Xu
prev parent reply other threads:[~2024-01-03 1:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-02 23:32 Suren Baghdasaryan
2024-01-03 1:54 ` Peter Xu [this message]
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