From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jann Horn <jannh@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Next Mailing List <linux-next@vger.kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Suren Baghdasaryan <surenb@google.com>
Subject: Re: linux-next: manual merge of the mm tree with Linus' tree
Date: Fri, 28 Jul 2023 10:00:47 +1000 [thread overview]
Message-ID: <20230728100047.4f9cd375@canb.auug.org.au> (raw)
In-Reply-To: <20230728092915.732d4115@canb.auug.org.au>
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Hi all,
On Fri, 28 Jul 2023 09:29:15 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> On Fri, 28 Jul 2023 09:18:49 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >
> > Today's linux-next merge of the mm tree got a conflict in:
> >
> > mm/memory.c
> >
> > between commit:
> >
> > 657b5146955e ("mm: lock_vma_under_rcu() must check vma->anon_vma under vma lock")
> >
> > from Linus' tree and commits:
> >
> > 69f6bbd1317f ("mm: handle userfaults under VMA lock")
> > a3bdf38e85aa ("mm: allow per-VMA locks on file-backed VMAs")
> >
> > from the mm tree.
> >
> > I fixed it up (I think, please check - see below) and can carry the fix
> > as necessary. This is now fixed as far as linux-next is concerned, but
> > any non trivial conflicts should be mentioned to your upstream
> > maintainer when your tree is submitted for merging. You may also want
> > to consider cooperating with the maintainer of the conflicting tree to
> > minimise any particularly complex conflicts.
> >
> > --
> > Cheers,
> > Stephen Rothwell
> >
> > diff --cc mm/memory.c
> > index ca632b58f792,271982fab2b8..000000000000
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@@ -5392,32 -5597,18 +5597,21 @@@ retry
> > if (!vma)
> > goto inval;
> >
> > - /* Only anonymous and tcp vmas are supported for now */
> > - if (!vma_is_anonymous(vma) && !vma_is_tcp(vma))
> > - /* find_mergeable_anon_vma uses adjacent vmas which are not locked */
> > - if (vma_is_anonymous(vma) && !vma->anon_vma)
> > -- goto inval;
> > --
> > if (!vma_start_read(vma))
> > goto inval;
> >
> > + /*
> > + * find_mergeable_anon_vma uses adjacent vmas which are not locked.
> > + * This check must happen after vma_start_read(); otherwise, a
> > + * concurrent mremap() with MREMAP_DONTUNMAP could dissociate the VMA
> > + * from its anon_vma.
> > + */
> > - if (unlikely(!vma->anon_vma && !vma_is_tcp(vma)))
> > - goto inval_end_read;
> > -
> > - /*
> > - * Due to the possibility of userfault handler dropping mmap_lock, avoid
> > - * it for now and fall back to page fault handling under mmap_lock.
> > - */
> > - if (userfaultfd_armed(vma))
> > ++ if (unlikely(vma_is_anonymous(vma) && !vma_is_tcp(vma)))
> > + goto inval_end_read;
> > +
> > /* Check since vm_start/vm_end might change before we lock the VMA */
> > - if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
> > - vma_end_read(vma);
> > - goto inval;
> > - }
> > + if (unlikely(address < vma->vm_start || address >= vma->vm_end))
> > + goto inval_end_read;
> >
> > /* Check if the VMA got isolated after we found it */
> > if (vma->detached) {
>
> Sorry, doesn't even build ... let me try that again.
I have gone with below. Again, please check.
--
Cheers,
Stephen Rothwell
diff --cc mm/memory.c
index ca632b58f792,271982fab2b8..000000000000
--- a/mm/memory.c
+++ b/mm/memory.c
@@@ -5392,32 -5597,18 +5597,21 @@@ retry
if (!vma)
goto inval;
- /* Only anonymous and tcp vmas are supported for now */
- if (!vma_is_anonymous(vma) && !vma_is_tcp(vma))
- /* find_mergeable_anon_vma uses adjacent vmas which are not locked */
- if (vma_is_anonymous(vma) && !vma->anon_vma)
-- goto inval;
--
if (!vma_start_read(vma))
goto inval;
+ /*
+ * find_mergeable_anon_vma uses adjacent vmas which are not locked.
+ * This check must happen after vma_start_read(); otherwise, a
+ * concurrent mremap() with MREMAP_DONTUNMAP could dissociate the VMA
+ * from its anon_vma.
+ */
- if (unlikely(!vma->anon_vma && !vma_is_tcp(vma)))
- goto inval_end_read;
-
- /*
- * Due to the possibility of userfault handler dropping mmap_lock, avoid
- * it for now and fall back to page fault handling under mmap_lock.
- */
- if (userfaultfd_armed(vma))
++ if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma))
+ goto inval_end_read;
+
/* Check since vm_start/vm_end might change before we lock the VMA */
- if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
- vma_end_read(vma);
- goto inval;
- }
+ if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+ goto inval_end_read;
/* Check if the VMA got isolated after we found it */
if (vma->detached) {
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next prev parent reply other threads:[~2023-07-28 0:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-27 23:18 linux-next: manual merge of the mm tree with Linus' tree Stephen Rothwell
2023-07-27 23:29 ` Stephen Rothwell
2023-07-27 23:40 ` Suren Baghdasaryan
2023-07-27 23:50 ` Matthew Wilcox
2023-07-28 0:08 ` Suren Baghdasaryan
2023-07-28 0:00 ` Stephen Rothwell [this message]
2023-07-28 3:13 ` Matthew Wilcox
2023-07-27 23:49 ` Matthew Wilcox
2023-07-28 0:21 ` Stephen Rothwell
2023-07-28 0:23 ` Suren Baghdasaryan
2023-07-28 0:29 ` Stephen Rothwell
2023-07-28 0:30 ` Suren Baghdasaryan
-- strict thread matches above, loose matches on Subject: below --
2023-07-06 22:54 Stephen Rothwell
2023-07-07 4:52 ` Baoquan He
2023-06-18 23:23 Stephen Rothwell
2023-06-19 20:25 ` Andrew Morton
2023-06-19 20:43 ` Will Deacon
2023-06-19 21:39 ` Andrew Morton
2023-06-20 9:43 ` Will Deacon
2023-06-20 15:00 ` Jain, Ayush
2023-02-24 23:39 Stephen Rothwell
2023-02-25 2:04 ` Andrew Morton
2023-02-25 7:13 ` Christian Brauner
2023-02-25 20:52 ` Andrew Morton
2023-02-27 10:18 ` Christian Brauner
2023-02-27 17:55 ` Andrew Morton
2022-11-07 2:52 Stephen Rothwell
2022-09-06 9:01 Stephen Rothwell
2022-09-06 9:21 ` Rolf Eike Beer
2022-05-26 6:09 Stephen Rothwell
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