All of lore.kernel.org
 help / color / mirror / Atom feed
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>,
	linux-kernel@vger.kernel.org,
	Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org,
	syzbot+9578faa5475acb35fa50@syzkaller.appspotmail.com,
	Mike Kravetz <mike.kravetz@oracle.com>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
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.
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

WARNING: multiple messages have this Message-ID (diff)
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.


  parent reply	other threads:[~2023-04-16 23:05 UTC|newest]

Thread overview: 22+ 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
2023-03-30 15:53 ` Ivan Orlov
2023-03-31  1:33 ` Zach O'Keefe via Linux-kernel-mentees
2023-03-31  1:33   ` Zach O'Keefe
2023-03-31  6:47   ` Ivan Orlov
2023-03-31  6:47     ` Ivan Orlov
2023-04-04  0:58   ` Yang Shi
2023-04-04  0:58     ` Yang Shi
2023-04-05 16:43     ` Zach O'Keefe via Linux-kernel-mentees
2023-04-05 16:43       ` Zach O'Keefe
2023-04-16 18:33       ` Andrew Morton
2023-04-16 18:33         ` Andrew Morton
2023-04-16 20:39         ` Ivan Orlov
2023-04-16 20:39           ` Ivan Orlov
2023-04-16 23:04         ` Ivan Orlov [this message]
2023-04-16 23:04           ` Ivan Orlov
2023-04-17  0:45         ` Hugh Dickins via Linux-kernel-mentees
2023-04-17  0:45           ` Hugh Dickins
2023-04-17 18:28         ` Ivan Orlov
2023-04-17 18:28           ` Ivan Orlov
2023-04-18 21:28           ` Andrew Morton
2023-04-18 21:28             ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d513cd8d-0262-8c4e-d0d9-ec7eea45941a@gmail.com \
    --to=ivan.orlov0322@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-kernel-mentees@lists.linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mike.kravetz@oracle.com \
    --cc=shy828301@gmail.com \
    --cc=syzbot+9578faa5475acb35fa50@syzkaller.appspotmail.com \
    --cc=willy@infradead.org \
    --cc=zokeefe@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.