linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Rongwei Wang <rongwei.wang@linux.alibaba.com>
To: Hugh Dickins <hughd@google.com>, Matthew Wilcox <willy@infradead.org>
Cc: Song Liu <song@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	William Kucharski <william.kucharski@oracle.com>
Subject: Re: [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache
Date: Sat, 2 Oct 2021 10:22:23 +0800	[thread overview]
Message-ID: <635ae57e-454e-0ef9-784d-3736b3bf44ac@linux.alibaba.com> (raw)
In-Reply-To: <f889db88-7b7d-ddb0-a7ed-3eda85d3eb96@google.com>



On 10/1/21 12:49 AM, Hugh Dickins wrote:
> On Thu, 30 Sep 2021, Matthew Wilcox wrote:
>> On Wed, Sep 29, 2021 at 10:24:44PM -0700, Hugh Dickins wrote:
>>>
>>> Aside from the above page->index mischeck in find_lock_entries(),
>>> I now think this bug needs nothing more than simply removing the
>>> VM_BUG_ON_PAGE(PageTail(page), page) from truncate_inode_page().
>>
>> I don't think that's right.  This bug was also observed when calling
>> truncate(), so there's clearly a situation where two concurrent calls
>> to truncate_pagecache() leaves a THP in the cache.
> 
> I assume you're thinking of one of the fuzzer blkdev ones:
> https://lore.kernel.org/linux-mm/CACkBjsbtF_peC7N_4mRfHML_BeiPe+O9DahTfr84puSG_J9rcQ@mail.gmail.com/
> or
> https://lore.kernel.org/lkml/CACkBjsYwLYLRmX8GpsDpMthagWOjWWrNxqY6ZLNQVr6yx+f5vA@mail.gmail.com/
> 
> I haven't started on those ones yet: yes, I imagine one or both of those
> will need a further fix (S_ISREG() check somewhere if we're lucky; but
> could well be nastier); but for the bug in this thread, I expect
> removing the VM_BUG_ON_PAGE(PageTail) to be enough.
Thanks for your advices!

I'm so sorry that delay the test due to my recent vacation. I plan to 
start further test tomorrow. I think removing the 
VM_BUG_ON_PAGE(PageTail) is a good idea, but also think using 
filemap_invalidate_lock is safer and necessary. And of course, this is 
just my own view! So, now, I tend to use filemap_invalidate_lock and
either check page mapping again or remove VM_BUG_ON_PAGE(PageTail).

Anyway, I will run more tests and then give feedback.

Thanks!
> 
> If you're thinking of something else, please send a link if you can - thanks.
> 
> Hugh
> 

  parent reply	other threads:[~2021-10-02  2:24 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06 12:11 [PATCH 0/2] mm, thp: fix file-backed THP race in collapse_file Rongwei Wang
2021-09-06 12:11 ` [PATCH 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-07  2:49   ` Yu Xu
2021-09-07 18:08   ` Yang Shi
     [not found]     ` <38AF4DC8-5E6F-4568-B2E3-0434BD847BC9@linux.alibaba.com>
2021-09-08 21:48       ` Yang Shi
2021-09-13 14:49   ` [mm, thp] 20753096b6: BUG:unable_to_handle_page_fault_for_address kernel test robot
2021-09-06 12:12 ` [PATCH 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-09-07 16:56   ` Yang Shi
     [not found]     ` <44BE85B4-692C-41E8-B5A0-C1E0B0272ACD@linux.alibaba.com>
2021-09-08 21:51       ` Yang Shi
2021-09-22  7:06 ` [PATCH v2 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-09-22  7:06 ` [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-22 11:37   ` Matthew Wilcox
2021-09-22 17:04     ` Rongwei Wang
2021-09-24  2:43       ` Andrew Morton
2021-09-24  3:08         ` Yang Shi
2021-09-24  3:35         ` Rongwei Wang
2021-09-24  7:12         ` Rongwei Wang
2021-09-27 22:24           ` Song Liu
2021-09-28 12:06             ` Matthew Wilcox
2021-09-28 16:59               ` Song Liu
2021-09-28 16:20             ` Rongwei Wang
2021-09-29  7:14               ` Song Liu
2021-09-29  7:50                 ` Rongwei Wang
2021-09-29 16:59                   ` Song Liu
2021-09-29 17:55                     ` Matthew Wilcox
2021-09-29 23:41                       ` Song Liu
2021-09-30  0:00                         ` Matthew Wilcox
2021-09-30  0:41                           ` Song Liu
2021-09-30  2:14                             ` Rongwei Wang
2021-10-04 17:26                             ` Rongwei Wang
2021-10-04 19:05                               ` Matthew Wilcox
2021-10-05  1:58                                 ` Rongwei Wang
2021-10-04 20:26                               ` Song Liu
2021-10-05  2:58                               ` Hugh Dickins
2021-10-05  3:07                                 ` Matthew Wilcox
2021-10-05  9:03                                 ` Rongwei Wang
2021-09-30  1:54                         ` Rongwei Wang
2021-09-30  3:26                           ` Song Liu
2021-09-30  5:24                             ` Hugh Dickins
2021-09-30 15:28                               ` Matthew Wilcox
2021-09-30 16:49                                 ` Hugh Dickins
2021-09-30 17:39                                   ` Yang Shi
2021-10-02 17:08                                     ` Matthew Wilcox
2021-10-04 18:28                                       ` Yang Shi
2021-10-04 19:31                                         ` Matthew Wilcox
2021-10-05  2:26                                           ` Hugh Dickins
2021-10-02  2:22                                   ` Rongwei Wang [this message]
2021-09-22  7:06 ` [PATCH v2 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06  2:18 ` [PATCH v3 v3 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-06  2:18   ` [PATCH v3 v3 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-06  2:18   ` [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06  2:41     ` Matthew Wilcox
2021-10-06  8:39       ` Rongwei Wang
2021-10-06 17:58     ` Yang Shi
2021-10-11  2:22 ` [PATCH v4 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-11  2:22   ` [PATCH v4 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-13  7:55     ` Rongwei Wang
2021-10-11  2:22   ` [PATCH v4 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-11  3:08     ` Matthew Wilcox
2021-10-11  3:22       ` Rongwei Wang
2021-10-11  5:08     ` [PATCH v4 RESEND " Rongwei Wang

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=635ae57e-454e-0ef9-784d-3736b3bf44ac@linux.alibaba.com \
    --to=rongwei.wang@linux.alibaba.com \
    --cc=akpm@linux-foundation.org \
    --cc=hughd@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=song@kernel.org \
    --cc=william.kucharski@oracle.com \
    --cc=willy@infradead.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).