From: Peter Xu <peterx@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Axel Rasmussen" <axelrasmussen@google.com>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Alexey Dobriyan" <adobriyan@gmail.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Chinwen Chang" <chinwen.chang@mediatek.com>,
"Huang Ying" <ying.huang@intel.com>,
"Ingo Molnar" <mingo@redhat.com>, "Jann Horn" <jannh@google.com>,
"Jerome Glisse" <jglisse@redhat.com>,
"Lokesh Gidra" <lokeshgidra@google.com>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Michal Koutný" <mkoutny@suse.com>,
"Michel Lespinasse" <walken@google.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Mike Rapoport" <rppt@linux.vnet.ibm.com>,
"Nicholas Piggin" <npiggin@gmail.com>, "Shaohua Li" <shli@fb.com>,
"Shawn Anastasio" <shawn@anastas.io>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Steven Price" <steven.price@arm.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, "Linux MM" <linux-mm@kvack.org>,
"Adam Ruprecht" <ruprecht@google.com>,
"Cannon Matthews" <cannonmatthews@google.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
"David Rientjes" <rientjes@google.com>,
"Mina Almasry" <almasrymina@google.com>,
"Oliver Upton" <oupton@google.com>
Subject: Re: [PATCH v5 05/10] userfaultfd: add minor fault registration mode
Date: Fri, 12 Feb 2021 17:44:05 -0500 [thread overview]
Message-ID: <20210212224405.GF3171@xz-x1> (raw)
In-Reply-To: <20210212222145.GB2858050@casper.infradead.org>
On Fri, Feb 12, 2021 at 10:21:45PM +0000, Matthew Wilcox wrote:
> On Thu, Feb 11, 2021 at 11:28:09AM -0800, Axel Rasmussen wrote:
> > Ah, I had added this just after VM_UFFD_WP, without noticing that this
> > would be sharing a bit with VM_LOCKED. That seems like not such a
> > great idea.
> >
> > I don't see another unused bit, and I don't see some other obvious
> > candidate to share with. So, the solution that comes to mind is
>
> it'd be even better if you didn't use the last unused bit for UFFD_WP.
> not sure how feasible that is, but you can see we're really short on
> bits here.
UFFD_WP is used now for anonymouse already.. And the support for hugetlbfs and
shmem is in rfc stage on the list.
Is it possible to use CONFIG_ARCH_USES_HIGH_VMA_FLAGS here? So far uffd-wp is
only working for 64 bit x86 too due to enlarged pte space. Maybe we can also
let minor mode to only support 64 bit hosts.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-02-12 22:49 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 21:21 [PATCH v5 00/10] userfaultfd: add minor fault handling Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 01/10] hugetlb: Pass vma into huge_pte_alloc() and huge_pmd_share() Axel Rasmussen
2021-02-11 23:59 ` Mike Kravetz
2021-02-10 21:21 ` [PATCH v5 02/10] hugetlb/userfaultfd: Forbid huge pmd sharing when uffd enabled Axel Rasmussen
2021-02-12 0:19 ` Mike Kravetz
2021-02-12 20:40 ` Peter Xu
2021-02-12 20:47 ` Axel Rasmussen
2021-02-12 21:27 ` Mike Kravetz
2021-02-10 21:21 ` [PATCH v5 03/10] mm/hugetlb: Move flush_hugetlb_tlb_range() into hugetlb.h Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 04/10] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp Axel Rasmussen
2021-02-12 18:11 ` Mike Kravetz
2021-02-12 21:18 ` Peter Xu
2021-02-12 21:34 ` Mike Kravetz
2021-02-12 22:14 ` Peter Xu
2021-02-10 21:21 ` [PATCH v5 05/10] userfaultfd: add minor fault registration mode Axel Rasmussen
2021-02-11 19:28 ` Axel Rasmussen
2021-02-11 20:58 ` Axel Rasmussen
2021-02-12 22:21 ` Matthew Wilcox
2021-02-12 22:44 ` Peter Xu [this message]
2021-02-12 22:51 ` Axel Rasmussen
2021-02-12 23:01 ` Peter Xu
2021-02-12 19:17 ` Mike Kravetz
2021-02-12 19:33 ` Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 06/10] userfaultfd: disable huge PMD sharing for MINOR registered VMAs Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 07/10] userfaultfd: hugetlbfs: only compile UFFD helpers if config enabled Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 08/10] userfaultfd: add UFFDIO_CONTINUE ioctl Axel Rasmussen
2021-02-10 22:21 ` Axel Rasmussen
2021-02-10 21:21 ` [PATCH v5 09/10] userfaultfd: update documentation to describe minor fault handling Axel Rasmussen
2021-02-10 21:22 ` [PATCH v5 10/10] userfaultfd/selftests: add test exercising " Axel Rasmussen
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