From: Hillf Danton <hdanton@sina.com>
To: Dimitris Siakavaras <jimsiak@cslab.ece.ntua.gr>
Cc: Axel Rasmussen <axelrasmussen@google.com>,
linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org
Subject: Re: Using userfaultfd with KVM's async page fault handling causes processes to hung waiting for mmap_lock to be released
Date: Thu, 20 Jul 2023 18:35:34 +0800 [thread overview]
Message-ID: <20230720103534.312-1-hdanton@sina.com> (raw)
In-Reply-To: <CAJHvVcj+Sc41mfercqxBii5cqRBEgZxNix2R1YMi04K-5nBh8w@mail.gmail.com>
On Wed, Jul 19, 2023 at 2:16 PM Axel Rasmussen <axelrasmussen@google.com> wrote:
>
> I think perhaps the right thing to do is to have handle_userfault() release
> mmap_lock when it returns VM_FAULT_NOPAGE, and to have GUP deal with that
> appropriately? But, some investigation is required to be sure that's okay to do
> in the other non-GUP ways we can end up in handle_userfault().
See if making kworker special works.
--- x/fs/userfaultfd.c
+++ y/fs/userfaultfd.c
@@ -457,6 +457,8 @@ vm_fault_t handle_userfault(struct vm_fa
* close the uffd.
*/
ret = VM_FAULT_NOPAGE;
+ if (current->flags & PF_WQ_WORKER)
+ ret = VM_FAULT_OOM;
goto out;
}
--
next prev parent reply other threads:[~2023-07-20 10:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <79375b71-db2e-3e66-346b-254c90d915e2@cslab.ece.ntua.gr>
2023-07-19 21:16 ` Axel Rasmussen
2023-07-19 21:54 ` Axel Rasmussen
2023-07-20 10:35 ` Hillf Danton [this message]
2023-07-20 20:07 ` Peter Xu
2023-07-20 20:06 ` Peter Xu
2025-03-07 7:21 ` Jinjiang Tu
2025-03-07 8:07 ` Jinjiang Tu
2025-03-07 13:11 ` jimsiak
2025-03-07 22:41 ` Peter Xu
2025-03-10 6:40 ` Jinjiang Tu
2025-03-10 18:50 ` Peter Xu
2025-03-11 8:14 ` Jinjiang Tu
2025-03-12 9:18 ` Jinjiang Tu
2025-03-12 14:09 ` Peter Xu
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