From: Ivan Orlov <ivan.orlov0322@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Zach O'Keefe <zokeefe@google.com>
Cc: Yang Shi <shy828301@gmail.com>,
himadrispandya@gmail.com, linux-kernel@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org,
linux-mm@kvack.org, skhan@linuxfoundation.org,
syzbot+9578faa5475acb35fa50@syzkaller.appspotmail.com,
Mike Kravetz <mike.kravetz@oracle.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2] mm: khugepaged: Fix kernel BUG in hpage_collapse_scan_file
Date: Mon, 17 Apr 2023 03:04:59 +0400 [thread overview]
Message-ID: <d513cd8d-0262-8c4e-d0d9-ec7eea45941a@gmail.com> (raw)
In-Reply-To: <20230416113335.caeafda1328fdd4bfe2406e8@linux-foundation.org>
On 4/16/23 22:33, Andrew Morton wrote:
>
> Circling back to this fix...
>
> The BUG() is obviously real. We're unsure that Ivan's fix is the best
> one. We haven't identified a Fixes:, and as this report is against the 6.2
> kernel, a cc:stable will be needed.
>
> According to the sysbot bisection
> (https://syzkaller.appspot.com/bug?id=7d6bb3760e026ece7524500fe44fb024a0e959fc),
> this is present in linux-5.19, so it might predate Zach's
> 58ac9a8993a13ebc changes. But that bisection claim might be
> misleading.
>
> And Zach is offline for a few months. So can people please take a look
> and see if we can get this wrapped up?
>
> Matthew, the assertion failure is in the
>
> VM_BUG_ON(index != xas.xa_index);
>
> which was added in 77da9389b9d5f, so perhaps you could take a look?
>
> Thanks.
I tested the reproducers on the 99cb0dbd47a15 commit, and they do not
trigger the problematic condition of shared memory truncation or
hole-punching. I will investigate further, as there have been many
changes in khugepaged since the 99cb0dbd47a15 commit that could
potentially affect its behavior.
next prev parent reply other threads:[~2023-04-16 23:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 15:53 [PATCH v2] mm: khugepaged: Fix kernel BUG in hpage_collapse_scan_file Ivan Orlov
2023-03-31 1:33 ` Zach O'Keefe
2023-03-31 6:47 ` Ivan Orlov
2023-04-04 0:58 ` Yang Shi
2023-04-05 16:43 ` Zach O'Keefe
2023-04-16 18:33 ` Andrew Morton
2023-04-16 20:39 ` Ivan Orlov
2023-04-16 23:04 ` Ivan Orlov [this message]
2023-04-17 0:45 ` Hugh Dickins
2023-04-17 18:28 ` Ivan Orlov
2023-04-18 21:28 ` Andrew Morton
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