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Date: Wed, 12 Jun 2024 12:30:05 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Xu <peterx@redhat.com>
Cc: syzbot <syzbot+0b56d6ed0d0c0c9a79dc@syzkaller.appspotmail.com>,
 linux-kernel@vger.kernel.org, linux-mm@kvack.org,
 pasha.tatashin@soleen.com, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [mm?] WARNING in __page_table_check_ptes_set (2)
Message-Id: <20240612123005.d5872e92a8f60e8dd459cdee@linux-foundation.org>
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On Wed, 12 Jun 2024 14:17:26 -0400 Peter Xu <peterx@redhat.com> wrote:

> Hi, Andrew,
> 
> On Wed, Jun 12, 2024 at 10:47:35AM -0700, Andrew Morton wrote:
> > On Wed, 12 Jun 2024 10:18:21 -0700 syzbot <syzbot+0b56d6ed0d0c0c9a79dc@syzkaller.appspotmail.com> wrote:
> > 
> > > Hello,
> > > 
> > > syzbot found the following issue on:
> > > 
> > > HEAD commit:    8867bbd4a056 mm: arm64: Fix the out-of-bounds issue in con..
> > > git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=146b3d96980000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=3b4350cf56c61c80
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=0b56d6ed0d0c0c9a79dc
> > > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > > userspace arch: arm64
> > > 
> > > Unfortunately, I don't have any reproducer for this issue yet.
> > >
> > > ...
> > >
> > > ------------[ cut here ]------------
> > > WARNING: CPU: 1 PID: 1 at mm/page_table_check.c:198 page_table_check_pte_flags mm/page_table_check.c:198 [inline]
> > > WARNING: CPU: 1 PID: 1 at mm/page_table_check.c:198 __page_table_check_ptes_set+0x324/0x398 mm/page_table_check.c:211
> > 
> > 	if (pte_present(pte) && pte_uffd_wp(pte))
> > 		WARN_ON_ONCE(pte_write(pte));
> > 
> > Let me optimistically cc Peter ;)
> 
> Looks like this is the same issue that the other patch wanted to fix:
> 
> [PATCH] mm/debug_vm_pgtable: Drop RANDOM_ORVALUE trick
> https://lore.kernel.org/r/20240523132139.289719-1-peterx@redhat.com
> 
> I had a look, and indeed that patch hasn't reached arm64/for-kernelci
> branch.

Thanks.

I currently have that patch queued for 6.11-rc1.  I'm thinking it
should have Fixes: 8430557fc5846 ("mm/page_table_check: support
userfault wr-protect entries") and that it should be moved to hotfixes
for 6.10-rcX, yes?