Re: [PATCH v8 00/23] userfaultfd-wp: Support shmem and hugetlbfs

From: Peter Xu <peterx@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Mike Kravetz <mike.kravetz@oracle.com>,
	David Hildenbrand <david@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Alistair Popple <apopple@nvidia.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Hugh Dickins <hughd@google.com>,
	Jerome Glisse <jglisse@redhat.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: Re: [PATCH v8 00/23] userfaultfd-wp: Support shmem and hugetlbfs
Date: Tue, 5 Apr 2022 19:02:32 -0400	[thread overview]
Message-ID: <YkzKiM8tI4+qOfXF@xz-m1.local> (raw)
In-Reply-To: <20220405154912.4cda03c2cc5d801d25d5c2dd@linux-foundation.org>

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On Tue, Apr 05, 2022 at 03:49:12PM -0700, Andrew Morton wrote:
> On Tue, 5 Apr 2022 18:42:43 -0400 Peter Xu <peterx@redhat.com> wrote:
> 
> > On Tue, Apr 05, 2022 at 03:16:16PM -0700, Andrew Morton wrote:
> > > On Mon,  4 Apr 2022 21:46:23 -0400 Peter Xu <peterx@redhat.com> wrote:
> > > 
> > > > This is v8 of the series to add shmem+hugetlbfs support for userfaultfd
> > > > write protection. 
> > > 
> > > Various compilation catastrophes with x86_64 allnoconfig.  I poked at
> > > the include ordering for a while but other things quickly became more
> > > attractive ;)
> > 
> > Sorry about that.  I still don't know what's the problem, but I'll give it
> > a shot soon.
> > 
> > I think I only tried out with the new configs but not all the rest configs.
> > I thought there're some bot looking after that one, from which I used to
> > receive build reports. And IIRC I fixed some build issues in early versions
> > from those reports.  Maybe I was wrong..
> > 
> > Any more hints on the latter?
> 
> `make allnoconfig'?
> 

Ah!  I thought when you mentioned "other things" you meant there're other
more severe issues... :)

For the allnoconfig, could you try with the attached quick fixup (upon
patch "mm/uffd: PTE_MARKER_UFFD_WP")?

That works for me on x86/arm, but I'm still trying out some other configs.

Thanks,

-- 
Peter Xu

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From 83dbc502eeaba12071413691374474c09e9f24bb Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Tue, 5 Apr 2022 19:00:37 -0400
Subject: [PATCH] fixup! mm/uffd: PTE_MARKER_UFFD_WP

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/linux/userfaultfd_k.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index ea11bed9bb7e..732b522bacb7 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -277,8 +277,12 @@ static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
 
 static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
 {
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
 	return is_pte_marker_entry(entry) &&
 	    (pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
+#else
+	return false;
+#endif
 }
 
 static inline bool pte_marker_uffd_wp(pte_t pte)
-- 
2.32.0

